海津 利行
| 基盤理工学専攻 | 准教授 |
| Ⅲ類（理工系） | 准教授 |
| 量子未来創生デバイス開発センター | 准教授 |
研究者情報
経歴
- 2024年10月 - 現在
電気通信大学, 量子未来創生デバイス開発センター, 准教授, 日本国 - 2022年05月 - 2024年10月
京都大学, 学際融合教育研究推進センター ナノテクノロジーハブ拠点, 特定研究員, 日本国 - 2021年04月 - 2022年03月
神戸大学, 大学院工学研究科 電気電子工学専攻, 助教, 日本国 - 2012年10月 - 2021年03月
神戸大学 研究基盤センター, Center for Supports to Research and Education Activities, 助教, 日本国 - 2010年04月 - 2012年09月
東京大学 先端科学技術研究センター, Research Center for Advanced Science and Technology, 特任助教 - 2007年04月 - 2010年03月
物質・材料研究機構 量子ドットセンター, ポスドク - 2005年10月 - 2007年03月
日本原子力研究開発機構 量子ビーム応用研究部門 放射光科学研究ユニット, 特定課題推進員 - 2004年04月 - 2005年09月
日本原子力研究所 放射光科学研究センター, 特定課題推進員
研究活動情報
論文
- Photo-Hall Effect Characterization and Terahertz Wave Generation with 1550 nm Excitation in InAs/GaAs Quantum Dot Superlattice Based Photoconductive Antenna
Y. Minami; A. Simmen; T. Kitada; Y. Harada; T. Kaizu; O. Kojima; T. Kita; O. Wada
Journal of Applied Physics, 出版日 2025年05月, 査読付, The basic photoconductive properties of an InAs/GaAs quantum dot (QD) superlattice have been characterized to develop photoconductive antennas (PCAs) operating with a telecom wavelength excitation for practical terahertz (THz) systems. The multiple-stacked InAs/GaAs QD structure was grown by molecular beam epitaxy and photo-Hall effect measurements were performed under infrared illumination conditions using light-emitting diodes with different emission wavelengths. The results have shown that the sign reversal occurs in the Hall coefficient (RH) as the illumination wavelength changes: RH is negative at 940 nm, and positive at 1550 nm. The photocurrent at 940 nm illumination is ascribed to the electron hole pair generation in QDs, whereas the photocurrent at 1550 nm is dominated by the hole current generated through the midgap states in the structure. The hole dominant photocurrent has been interpreted by a model in which photogenerated electrons are trapped in QDs and the number of mobile electrons are reduced. High dark resistance of the present QD superlattice material provides an advantage for the application to PCA devices. THz wave generation has been demonstrated by the ultrafast 1550 nm pulse excitation of a PCA device fabricated from the QD superlattice.
研究論文（学術雑誌）, 英語 - Lateral photoconductivity of InAs/GaAs quantum dots for 1.5 μm-wavelength excitation photoconductive terahertz antenna devices
Toshiyuki Kaizu; Osamu Kojima; Yasuo Minami; Takahiro Kitada; Yukihiro Harada; Takashi Kita; Osamu Wada
筆頭著者, Japanese Journal of Applied Physics, IOP Publishing, 63巻, 8号, 掲載ページ 082002-1-5, 出版日 2024年08月01日, 査読付, We report lateral photoconductive properties of multilayer-stacked undoped InAs/GaAs quantum dots (QDs) for the application of photoconductive terahertz (THz) antenna devices that operate in a 1.5 μm-telecom-wavelength band. The excitation power-dependent photocurrent showed a high value without saturation under high excitation power for the excitation wavelength of 1460 nm. From the reflection pump-probe signal, a fast photocarrier lifetime was derived. These results, together with the low dark current characteristic, support the applicability of the multilayer-stacked undoped InAs/GaAs QDs to photoconductive THz antennas operating in a 1.5 μm-wavelength band.
研究論文（学術雑誌） - Yb-doped Y–Al–O thin films with a self-organized columnar structure and their anti-Stokes photoluminescence properties
Y. Nakayama; N. Nakagawa; Y. Matsuo; T. Kaizu; Y. Harada; T. Ishihara; T. Kita
AIP Advances, AIP Publishing, 12巻, 2号, 掲載ページ 025110-1-8, 出版日 2022年02月01日, 査読付
研究論文（学術雑誌） - Polarization-insensitive fiber-to-fiber gain of semiconductor optical amplifier using closely stacked InAs/GaAs quantum dots
Toshiyuki Kaizu; Tomoya Kakutani; Kouichi Akahane; Takashi Kita
筆頭著者, Japanese Journal of Applied Physics, IOP Publishing, 59巻, 3号, 掲載ページ 032002-1-5, 出版日 2020年02月17日, 査読付
研究論文（学術雑誌） - Photoelectrochemical Reaction in an Electric Cell with a Porous Carbon Anode
Toshiyuki Kaizu; Yousuke Kawajiri; Masahito Enomoto; Takashi Uchino; Minoru Mizuhata; Yuichi Ichihashi; Keita Taniya; Satoru Nishiyama; Masakazu Sugiyama; Masami Ueno; Takashi Kita
The Journal of Physical Chemistry C, American Chemical Society (ACS), 123巻, 32号, 掲載ページ 19447-19452, 出版日 2019年07月24日
研究論文（学術雑誌） - Wide-wavelength-range control of photoluminescence polarization in closely stacked inas/gaas quantum dots
Toshiyuki Kaizu; Yusuke Tajiri; Takashi Kita
筆頭著者, Journal of Applied Physics, American Institute of Physics Inc., 125巻, 23号, 掲載ページ 234304-1-8, 出版日 2019年06月21日, 査読付, 国際誌, We developed a method of growing closely stacked InAs/GaAs quantum dots (QDs) to control the photoluminescence (PL) polarization characteristics in a wide wavelength range. The emission wavelength of the closely stacked QDs redshifted with decreasing substrate temperature during stacking growth, while the PL polarization characteristic was controlled by the GaAs spacer layer thickness and the number of QD layers. A unified rule for the optimum GaAs spacer layer thickness that both enhances the transverse magnetic (TM)-polarized component and achieves a high PL intensity for all growth temperatures was revealed. 30-layer stacked QDs with the optimum spacer layer thickness grown at substrate temperatures from 430 to 480 °C exhibited TM-enhanced polarization characteristics in the 1.15-1.3 μm band. Moreover, we studied the one-dimensional electronic states in the closely stacked QDs with the optimized GaAs spacer layer thickness by time-resolved PL.
研究論文（学術雑誌）, 英語 - Adiabatic two-step photoexcitation effects in intermediate-band solar cells with quantum dot-in-well structure
S. Asahi,T. Kaizu,T. Kita
Scientific Reports, Nature Publishing Group, 9巻, 掲載ページ 7859-1-8, 出版日 2019年05月, 査読付, We studied the dynamics of electrons generated by two-step photoexcitation in an intermediate-band solar cell (IBSC) comprising InAs/GaAs/Al0.3Ga0.7As dot-in-well (DWELL) structure using time-resolved photocurrent (TRPC) measurement. The examined IBSC exhibited considerably slower photocurrent decay than a conventional InAs/GaAs quantum dot IBSC, which is due to the extraordina
研究論文（学術雑誌）, 英語 - Carrier collection efficiency of intraband-excited carriers in two-step photon up-conversion solar cells
Shigeo Asahi; Kenta Nishimura; Toshiyuki Kaizu; Takashi Kita
2018 IEEE 7th World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - A Joint Conference of 45th IEEE PVSC, 28th PVSEC and 34th EU PVSEC, Institute of Electrical and Electronics Engineers Inc., 掲載ページ 3447-3450, 出版日 2018年11月26日, Recently, we have proposed a new type solar cells utilizing photon up-conversion phenomenon, called two-step photon up-conversion solar cells for realizing high conversion efficiency solar cells. Here, achieving efficient intraband photoexcitation is indispensable. This solar cell has a simple single- j unction structure containing a hetero-interface. In this study, we investigated the applying electric field dependence of two-step photon up-conversion occurring at the hetero-interface. We found that dense electron accumulation and an appropriate electric field enable to dramatically increase the intraband excitation strength and the carrier collection efficiency at the hetero-interface.
研究論文（国際会議プロシーディングス）, 英語 - Two-step photocurrent generation enhanced by the fundamental-state miniband formation in intermediate-band solar cells using a highly homogeneous InAs/GaAs quantum-dot superlattice
Kazuki Hirao; Shigeo Asahi; Toshiyuki Kaizu; Takashi Kita
Applied Physics Express, IOP PUBLISHING LTD, 11巻, 1号, 掲載ページ 012301-1-4, 出版日 2018年01月, 査読付, We studied intermediate-band solar cells (IBSCs) incorporating highly homogeneous InAs/GaAs quantum dot superlattices (QDSLs). The extra photocurrent generated by two-step photon absorption markedly increases at the fundamental state (FS) because the FS miniband has been successfully formed in the QDSL-IBSC by controlling the QD size homogeneity. Here, the carriers excited into the miniband spatially separate in the internal electric field, and the long-lived electrons in the intermediate states of the miniband increase the inter-subband absorption strength. The two-step photocurrent response, therefore, extends toward the longer-wavelength side corresponding to the QDSL-FS at approximately 1.2 mu m. (C) 2018 The Japan Society of Applied Physics
研究論文（学術雑誌）, 英語 - Spatially resolved electronic structure of an isovalent nitrogen center in GaAs
R. C. Plantenga; V. R. Kortan; T. Kaizu; Y. Harada; T. Kita; M. E. Flatte; P. M. Koenraad
Physical Review B, AMER PHYSICAL SOC, 96巻, 15号, 掲載ページ 155210-1-8, 出版日 2017年10月, 査読付, Small numbers of nitrogen dopants dramatically modify the electronic properties of GaAs, generating spatially localized resonant states within the conduction band, pair and cluster states in the band gap, and very large shifts in the conduction-band energies with nonlinear concentration dependence. Cross-sectional scanning tunneling microscopy provides the local electronic structure of single nitrogen dopants at the (110) GaAs surface, yielding highly anisotropic spatial shapes when the empty states are imaged. Measurements of the resonant states relative to the GaAs surface states and their spatial extent allow an unambiguous assignment of specific features to nitrogen atoms at different depths below the cleaved (110) surface. Multiband tight-binding calculations around the resonance energy of nitrogen in the conduction band match the imaged features, verifying that the Green's function method can accurately describe the isolated isovalent nitrogen impurity. The spatial anisotropy is attributed to the tetrahedral symmetry of the bulk lattice and will lead to a directional dependence for the interaction of nitrogen atoms. Additionally, the voltage dependence of the electronic contrast for two features in the filled state imaging suggests these features could be related to a locally modified surface state.
研究論文（学術雑誌）, 英語 - Efficient two-step photocarrier generation in bias-controlled InAs/GaAs quantum dot superlattice intermediate-band solar cells
T. Kada; S. Asahi; T. Kaizu; Y. Harada; R. Tamaki; Y. Okada; T. Kita
Scientific Reports, NATURE PUBLISHING GROUP, 7巻, 掲載ページ 5865-1-10, 出版日 2017年07月, 査読付, We studied the effects of the internal electric field on two-step photocarrier generation in InAs/GaAs quantum dot superlattice (QDSL) intermediate-band solar cells (IBSCs). The external quantum efficiency of QDSL-IBSCs was measured as a function of the internal electric field intensity, and compared with theoretical calculations accounting for interband and intersubband photoexcitations. The extra photocurrent caused by the two-step photoexcitation was maximal for a reversely biased electric field, while the current generated by the interband photoexcitation increased monotonically with increasing electric field intensity. The internal electric field in solar cells separated photogenerated electrons and holes in the superlattice (SL) miniband that played the role of an intermediate band, and the electron lifetime was extended to the microsecond scale, which improved the intersubband transition strength, therefore increasing the two-step photocurrent. There was a trade-off relation between the carrier separation enhancing the two-step photoexcitation and the electric-field-induced carrier escape from QDSLs. These results validate that long-lifetime electrons are key to maximising the two-step photocarrier generation in QDSL-IBSCs.
研究論文（学術雑誌）, 英語 - Two-step photocurrent generation enhanced by miniband formation in InAs/GaAs quantum dot superlattice intermediate-band solar cells
Sho Watanabe; Shigeo Asahi; Tomoyuki Kada; Kazuki Hirao; Toshiyuki Kaizu; Yukihiro Harada; Takashi Kita
Applied Physics Letters, AMER INST PHYSICS, 110巻, 19号, 掲載ページ 193104-1-5, 出版日 2017年05月, 査読付, We studied the effects of miniband formation on the photocurrent generated by two-step intersubband absorption in an intermediate-band solar cell incorporating an InAs/GaAs quantum dot superlattice (QDSL). The two-step photocarrier generation increases with the electronic state coupling of InAs QDSLs in the intrinsic layer. Because carriers that are excited into the superlattice minibands spatially separate in an internal electric field, the electron-hole recombination rate for the photoexcited carriers decreases, and therefore, the electron lifetime increases. The long-lived electrons in the intermediate states of the QDSL miniband increase the intersubband absorption strength. We confirmed a systematic sensitive change in the two-step photocurrent generation depending on the miniband formation controlled by the temperature. Published by AIP Publishing.
研究論文（学術雑誌）, 英語 - Two-step photon up-conversion solar cells
Shigeo Asahi; Haruyuki Teranishi; Kazuki Kusaki; Toshiyuki Kaizu; Takashi Kita
Nature Communications, NATURE PUBLISHING GROUP, 8巻, 掲載ページ 14962-1-9, 出版日 2017年04月, 査読付, Reducing the transmission loss for below-gap photons is a straightforward way to break the limit of the energy-conversion efficiency of solar cells (SCs). The up-conversion of below-gap photons is very promising for generating additional photocurrent. Here we propose a two-step photon up-conversion SC with a hetero-interface comprising different bandgaps of Al0.3Ga0.7As and GaAs. The below- gap photons for Al0.3Ga0.7As excite GaAs and generate electrons at the hetero-interface. The accumulated electrons at the hetero-interface are pumped upwards into the Al0.3Ga0.7As barrier by below- gap photons for GaAs. Efficient two-step photon up-conversion is achieved by introducing InAs quantum dots at the hetero-interface. We observe not only a dramatic increase in the additional photocurrent, which exceeds the reported values by approximately two orders of magnitude, but also an increase in the photovoltage. These results suggest that the two-step photon up-conversion SC has a high potential for implementation in the next-generation high-efficiency SCs.
研究論文（学術雑誌）, 英語 - Transverse-magnetic laser oscillation from highly stacked InAs/GaAs quantum dots
Toshiyuki Kaizu; Masaya Suwa; Takaya Andachi; Yukihiro Harada; Takashi Kita
Conference Digest - IEEE International Semiconductor Laser Conference, Institute of Electrical and Electronics Engineers Inc., 出版日 2016年12月02日, We studied electroluminescence and net-modal gain in 40-stacked InAs/GaAs quantum dot (QD) laser devices. Since the electronic coupling between the QDs enhanced the transverse-magnetic (TM) component, the [110] waveguide devices exhibited a laser oscillation in the TM component as well as the transverse-electric (TE) component.
研究論文（国際会議プロシーディングス）, 英語 - Photocarrier transport dynamics in InAs/GaAs quantum dot superlattice solar cells using time-of-flight spectroscopy
T. Tanibuchi; T. Kada; S. Asahi; D. Watanabe; T. Kaizu; Y. Harada; T. Kita
Physical Review B, AMER PHYSICAL SOC, 94巻, 19号, 掲載ページ 1-9, 出版日 2016年11月, 査読付, We studied time-resolved photocarrier transport through InAs/GaAs quantum dot superlattice (QDSL) solar cells (SCs) using time-of-flight spectroscopy with an optical probe QD structure beneath the QDSL. Carriers optically pumped in the top p-GaAs layer were transported through the intrinsic layer, including the QDSLs, before arriving at the probe QDs. The photoexcited carrier density significantly influenced the time-resolved photoluminescence (PL) of the QDSLs and probe QDs. The time-resolved PL profile of the probe QDs indicated that excitation densities in excess of 25nJ/cm(2) drastically decreased the rise time, suggesting rapid carrier transport through the QDSLs. This was also confirmed by QDSL carrier transport dynamics, for which the PL intensity of the excited states decayed rapidly above this excitation power density, 25nJ/cm(2), while the ground state remained constant. These results demonstrate that filling the ground states of QDSLs and starting to populate the excited state miniband accelerates carrier transport in QDSL SCs. Furthermore, according to two-step photon absorption measurements taken with a 1.3-mu m infrared laser light source, electrons play a key role in the generation of extra photocurrent by sub-band-gap photon irradiation.
研究論文（学術雑誌）, 英語 - Polarization characteristics of electroluminescence and net modal gain in highly stacked InAs/GaAs quantum-dot laser devices
Masaya Suwa; Takaya Andachi; Toshiyuki Kaizu; Yukihiro Harada; Takashi Kita
Journal of Applied Physics, AMER INST PHYSICS, 120巻, 13号, 掲載ページ 1-6, 出版日 2016年10月, 査読付, We studied the polarization anisotropy of electroluminescence (EL) and net modal gain characteristics of laser device structures containing 40 stacked InAs/GaAs quantum dot (QD) layers. The electronic coupling between the closely stacked QDs enhanced the transverse-magnetic (TM) polarization component owing to the heavy-and light-hole mixing. Thereby, the [110]-waveguide devices exhibited a laser oscillation of not only the transverse-electric (TE) but also the TM component. Laser oscillation occurred at 1137nm from the first excited state for the 300-mu m-long cavity, while it occurred at 1167 nm from the ground state for the 1000-mu m-long cavity. The polarization anisotropy of the EL intensity strongly depended on the injection current density. The polarized EL intensity was almost isotropic at low injection current density. As the injection current density was increased, the TE component was gradually enhanced, which resulted in a markedly TE-dominant anisotropy above the threshold current density for laser oscillation. The net modal gains evaluated using the Hakki-Paoli method also exhibited a TE-enhanced characteristic with increasing injection current density. As the EL spectra of the TE component have an inhomogeneous broadening narrower than that of the TM component, the TE-mode intensity is likely to be enhanced by the concentration of the injected carriers. Published by AIP Publishing.
研究論文（学術雑誌）, 英語 - Emission-wavelength tuning of InAs quantum dots grown on nitrogen-delta-doped GaAs(001)
Toshiyuki Kaizu; Kohei Taguchi; Takashi Kita
筆頭著者, Journal of Applied Physics, AMER INST PHYSICS, 119巻, 19号, 掲載ページ 194306-1-8, 出版日 2016年05月, 査読付, We studied the structural and photoluminescence (PL) characteristics of InAs quantum dots (QDs) grown on nitrogen (N) (5-doped GaAs(001). The emission wavelength for low-density N-delta doping exhibited a blueshift with respect to that for undoped GaAs and was redshifted with increasing N-sheet density. This behavior corresponded to the variation in the In composition of the QDs. N-delta doping has two opposite and competing effects on the incorporation of Ga atoms from the underlying layer into the QDs during the QD growth. One is the enhancement of Ga incorporation induced by the lattice strain, Which is due to the smaller radius of N atoms. The other is an effect blocking for Ga incorporation, which is due to the large bonding energy of Ga-N or In-N. At a low N-sheet density, the lattice-strain effect was dominant, while the blocking effect became larger with increasing N-sheet density, Therefore, the incorporation of Ga from the underlying layer depended on the N-sheet density. Since the In-Ga intermixing between the QDs and the GaAs cap layer during capping also depended on the size of the as-grown QDs, which was affected by the N-sheet density, the superposition of these three factors determined the composition of the QDs. in addition, the piezoelectric effect, which was induced with increased accumulation of lattice strain and the associated high In composition, also affected the PL properties of the QDs. As a result, tuning of the emission wavelength from 1. to 1.26 mu m was achieved at room temperature. Published by AIP Publishing.
研究論文（学術雑誌）, 英語 - Saturable Two-Step Photocurrent Generation in Intermediate-Band Solar Cells Including InAs Quantum Dots Embedded in Al0.3Ga0.7As/GaAs Quantum Wells
Shigeo Asahi; Haruyuki Teranishi; Naofumi Kasamatsu; Tomoyuki Kada; Toshiyuki Kaizu; Takashi Kita
IEEE Journal of Photovoltaics, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 6巻, 2号, 掲載ページ 465-472, 出版日 2016年03月, 査読付, We studied in detail the photocurrent generation process in two-step photon absorption in intermediate-band solar cells, including InAs quantum dots embedded in Al0.3Ga0.7As/GaAs quantum wells at room temperature. The photocurrent generated by the two-step photon absorption exhibited saturation as the interband excitation intensity increased in strength. On the other hand, as the intersubband excitation intensity increased, the two-step photoexcitation current deviated from a power law. Furthermore, the two-step photoexcitation current exhibiting saturation and deviation strongly depended on both the interband and intersubband excitation intensities. To interpret these phenomena, we performed a theoretical simulation of the two-step photoexcitation current. The results suggest that the photocurrent saturation and deviation were caused by filling of the intermediate states with electrons. Furthermore, our calculated results indicate that the electron-recombination lifetime in the intermediate states is extremely long. The results of the temperature dependence of the two-step photoexcitation current and the excitation intensity dependence of photoluminescence suggest that efficient electron-hole separation extends electron lifetime.
研究論文（学術雑誌）, 英語 - Effects of rapid thermal annealing on two-dimensional delocalized electronic states of the epitaxial N delta-doped layer in GaAs
Yasuhiro Ogawa; Yukihiro Harada; Takeshi Baba; Toshiyuki Kaizu; Takashi Kita
Applied Physics Letters, AMER INST PHYSICS, 108巻, 11号, 掲載ページ 1~4, 出版日 2016年03月, 査読付, We have conducted rapid thermal annealing (RTA) for improving the two-dimensional (2D) arrangement of electronic states in the epitaxial nitrogen (N) delta-doped layer in GaAs. RTA rearranged the N-pair configurations in the GaAs (001) plane and reduced the number of non-radiative recombination centers. Furthermore, a Landau shift, representing the 2D delocalized electronic states in the (001) plane, was observed at around zero magnetic field intensity in the Faraday configuration. (C) 2016 AIP Publishing LLC.
研究論文（学術雑誌）, 英語 - Polarization anisotropy of electroluminescence and net-modal gain in highly stacked InAs/GaAs quantum-dot laser devices
Toshiyuki Kaizu; Masaya Suwa; Takaya Andachi; Yukihiro Harada; Takashi Kita
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), IEEE, 出版日 2016年, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Transverse-magnetic laser oscillation from highly stacked InAs/GaAs quantum dots
Toshiyuki Kaizu; Masaya Suwa; Takaya Andachi; Yukihiro Harada; Takashi Kita
2016 INTERNATIONAL SEMICONDUCTOR LASER CONFERENCE (ISLC), IEEE, 出版日 2016年, 査読付, We studied electroluminescence and net-modal gain in 40-stacked InAs/GaAs quantum dot (QD) laser devices. Since the electronic coupling between the QDs enhanced the transverse-magnetic (TM) component, the [110] waveguide devices exhibited a laser oscillation in the TM component as well as the transverse-electric (TE) component.
研究論文（国際会議プロシーディングス）, 英語 - Two-Dimensional Energy Dispersion in Thermally Annealed Epitaxial Nitrogen Atomic Sheet in GaAs
Yasuhiro Ogawa; Yukihiro Harada; Kaizu Toshiyuki; Takashi Kita
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), IEEE, 出版日 2016年, 査読付
研究論文（国際会議プロシーディングス）, 英語 - GaAs first-spacer-layer thickness dependence of polarized photoluminescence properties of closely-stacked InAs/GaAs quantum dots with long-wavelength emission
Yusuke Tajiri; Toshiyuki Kaizu; Takashi Kita
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), IEEE, 出版日 2016年, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Broadband control of emission wavelength of InAs/GaAs quantum dots by GaAs capping temperature
Toshiyuki Kaizu; Takuya Matsumura; Takashi Kita
筆頭著者, Journal of Applied Physics, AMER INST PHYSICS, 118巻, 15号, 掲載ページ 154301-1-6, 出版日 2015年10月, 査読付, We investigated the effects of the GaAs capping temperature on the morphological and photoluminescence (PL) properties of InAs quantum dots (QDs) on GaAs(001). The broadband tuning of the emission wavelength from 1.1 to 1.3 mu m was achieved at room temperature by only adjusting the GaAs capping temperature. As the capping temperature was decreased, the QD shrinkage due to In desorption and In-Ga intermixing during the capping process was suppressed. This led to QDs with a high aspect ratio, and resultantly, the emission wavelength shifted toward the longer-wavelength side. In addition, the linearly polarized PL intensity elucidated anisotropic characteristics reflecting the shape anisotropy of the embedded QDs, in which a marked change in polarization anisotropy occurred at capping temperatures lower than 460 degrees C. (C) 2015 AIP Publishing LLC.
研究論文（学術雑誌）, 英語 - InAs/GaAs/Al0.3Ga0.7As 中間バンド型太陽電池における室温2段階光励起の飽和現象の解析
朝日 重雄; 寺西 陽之; 笠松 直史; 加田 智之; 海津 利行; 喜多 隆
材料, The Society of Materials Science, Japan, 64巻, 9号, 掲載ページ 690-695, 出版日 2015年09月01日, 査読付, We systematically studied two-step photocurrent generation as functions of the excitation intensities for the inter-band and inter-subband transitions in an InAs/GaAs/Al<sub>0.3</sub>Ga<sub>0.7</sub>As dot-in-well (DWELL) intermediate-band solar cell.The two-step photoexcitation current shows saturation as the inter-band excitation intensity becomes strong, and we found that th
研究論文（学術雑誌）, 日本語 - 近接積層InAs/GaAs量子ドット半導体光アンプの光導波モード解析
諏訪 雅也; 大橋 知幸; 安達 貴哉; 海津 利行; 原田 幸弘; 喜多 隆
材料, Society of Materials Science Japan, 64巻, 9号, 掲載ページ 685-689, 出版日 2015年09月01日, 査読付, We performed modal analysis for 40-stacked InAs/GaAs quantum dot semiconductor optical amplifiers (QDSOAs) as a function of the waveguide width using an equivalent refractive index technique. QDSOAs with 5- and 11-μm-waveguide widths show multi-mode operations. The theoretical simulation reproduced well the experimental electroluminescence spectrum and unveiled that the output signals comprise several transverse modes. Besides, we confirmed a waveguide width less than 1.28 μm is essential to realize single-mode QDSOAs. The modal gain spectra were analyzed by using the Hakki-Paoli method. Multi peaks arisen from the multi-mode operation were also observed in the gain spectrum, suggesting precise control of the transverse mode is important for a practical realization of the single-mode device.
研究論文（学術雑誌）, 日本語 - Two-step photon absorption in InAs/GaAs quantum-dot superlattice solar cells
T. Kada; S. Asahi; T. Kaizu; Y. Harada; T. Kita; R. Tamaki; Y. Okada; K. Miyano
Physical Review B, AMER PHYSICAL SOC, 91巻, 20号, 掲載ページ 201303-1-6, 出版日 2015年05月, 査読付, We studied the two-step photon absorption (TSPA) process in InAs/GaAs quantum-dot superlattice (QDSL) solar cells. TSPA of subband-gap photons efficiently occurs when electrons are pumped from the valence band to the states above the inhomogeneously distributed fundamental states of QDSLs. The photoluminescence (PL)-excitation spectrum demonstrates an absorption edge attributed to the higher excited states of the QDSLs in between the InAs wetting layer states and the fundamental states of QDSLs. When the absorption edge of the excited state was resonantly excited, the superlinear excitation power dependence of the PL intensity demonstrated that the electron and hole created by the interband transition separately relax into QDSLs. Furthermore, time-resolved PL measurements demonstrated that the electron lifetime is extended by thereby inhibiting recombination with holes, enhancing the second subband-gap absorption.
研究論文（学術雑誌）, 英語 - Saturable Two-step Photo current Generation in Intermediate-band Solar Cells Including InAs Quantum Dots Embedded in Al0.3Ga0.7As/GaAs Quantum Wells
Shigeo Asahi; Haruyuki Teranishi; Naofumi Kasamatsu; Tomoyuki Kada; Toshiyuki Kaizu; Takashi Kita
2015 IEEE 42ND PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), IEEE, 出版日 2015年, 査読付, We have studied detailed photocurrent generation process in the two-step photon absorption in intermediate-band solar cells including InAs quantum dots embedded in Al0.3Ga0.7As/GaAs quantum wells and influence of thermal carrier escape at room temperature. The photocurrent generated by the two-step photon absorption shows saturation as the inter-band excitation intensity becomes strong. and the inter-band excitation intensity showing the saturation behavior strongly depends on the inter-subband excitation intensity. To interpret this phenomenon. we carried out a theoretical simulation based on carrier dynamics considering carrier generation. energy relaxation and thermal carrier escape. The results indicate that the photocurrent saturation is caused by filling the intermediate states with electrons. The shift of the saturation point depending on the inter-subband excitation intensity is caused by the shift of the quasi-Fermi level for the intermediate states.
研究論文（国際会議プロシーディングス）, 英語 - Two-Step Photocarrier Generation in InAs/GaAs Quantum Dot Superlattice Intermediate Band Solar Cell
Tomoyuki Kada; Taizo Tanibuchi; Shigeo Asahi; Toshiyuki Kaizu; Yukihiro Harada; Takashi Kita; Ryo Tamaki; Yoshitaka Okada; Kenjiro Miyano
2015 IEEE 42ND PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), 出版日 2015年, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Suppression of thermal carrier escape and enhanced two-step photon absorption in quantum-dot intermediate-band solar cells with a high-potential barrier
S. Asahi; H. Teranishi; N. Kasamatsu; T. Kada; T. Kaizu; T. Kita
PHYSICS SIMULATION AND PHOTONIC ENGINEERING OF PHOTOVOLTAIC DEVICES IV, SPIE-INT SOC OPTICAL ENGINEERING, 9358巻, 出版日 2015年, We have studied detailed carrier generation process in the two-step photon absorption and influence of thermal carrier escape in quantum-dot intermediate-band solar cells (QD-IBSC). The photocurrent created by the two-step photon absorption shows saturation as the inter-band excitation intensity becomes strong, and the inter-band excitation intensity showing the saturation behavior strongly depends on the inter-subband excitation intensity. To interpret this phenomenon, we carried out a theoretical simulation based on carrier dynamics considering carrier generation, energy relaxation and thermal carrier escape. The results indicate that the photocurrent saturation is caused by filling the intermediate states. The shift of the saturation point depending on the inter-subband excitation intensity is caused by the shift of the quasi-Fermi level for the intermediate states.
研究論文（国際会議プロシーディングス）, 英語 - Photoluminescence Properties of InAs Quantum Dots on Nitrogen δ-Doped GaAs
T. Kaizu; T. Kita
14th International Symposium on Advanced Fluid Information, 掲載ページ 148-149, 出版日 2014年11月
研究論文（国際会議プロシーディングス）, 英語 - Suppression of exciton-spin relaxation induced by artificial lateral quantum confinement in GaAs
Takayuki Kiba; T. Tanaka; Yosuke Tamura; Cedric Thomas; Toshiyuki Kaizu; Yoshitaka Okada; Seiji Samukawa; Akihiro Murayama
18th International Conference on Molecular Beam Epitaxy, 出版日 2014年09月, 査読付
研究論文（国際会議プロシーディングス）, 英語 - Suppression of thermal carrier escape and efficient photo-carrier generation by two-step photon absorption in InAs quantum dot intermediate-band solar cells using a dot-in-well structure
S. Asahi; H. Teranishi; N. Kasamatsu; T. Kada; T. Kaizu; T. Kita
Journal of Applied Physics, AMER INST PHYSICS, 116巻, 6号, 掲載ページ 063510-1-5, 出版日 2014年08月, 査読付, We investigated the effects of an increase in the barrier height on the enhancement of the efficiency of two-step photo-excitation in InAs quantum dot (QD) solar cells with a dot-in-well structure. Thermal carrier escape of electrons pumped in QD states was drastically reduced by sandwiching InAs/GaAs QDs with a high potential barrier of Al0.3Ga0.7As. The thermal activation energy increased with the introduction of the barrier. The high potential barrier caused suppression of thermal carrier escape and helped realize a high electron density in the QD states. We observed efficient two-step photon absorption as a result of the high occupancy of the QD states at room temperature. (C) 2014 AIP Publishing LLC.
研究論文（学術雑誌）, 英語 - Polarization-insensitive optical gain characteristics of highly stacked InAs/GaAs quantum dots
Takashi Kita; Masaya Suwa; Toshiyuki Kaizu; Yukihiro Harada
Journal of Applied Physics, AMER INST PHYSICS, 115巻, 23号, 掲載ページ 233512-1-5, 出版日 2014年06月, 査読付, The polarized optical gain characteristics of highly stacked InAs/GaAs quantum dots (QDs) with a thin spacer layer fabricated on an n(+)-GaAs (001) substrate were studied in the sub-threshold gain region. Using a 4.0-nm-thick spacer layer, we realized an electronically coupled QD superlattice structure along the stacking direction, which enabled the enhancement of the optical gain of the [001] transverse-magnetic (TM) polarization component. We systematically studied the polarized electroluminescence properties of laser devices containing 30 and 40 stacked InAs/GaAs QDs. The net modal gain was analyzed using the Hakki-Paoli method. Owing to the in-plane shape anisotropy of QDs, the polarization sensitivity of the gain depends on the waveguide direction. The gain showing polarization isotropy between the TM and transverse-electric polarization components is high for the [110] waveguide structure, which occurs for higher amounts of stacked QDs. Conversely, the isotropy of the [similar to 110] waveguide is easily achieved even if the stacking is relatively low, although the gain is small. (C) 2014 AIP Publishing LLC.
研究論文（学術雑誌）, 英語 - Theoretical analysis of GaAs/AlGaAs quantum dots in quantum wire array for intermediate band solar cell
T. Sogabe; T. Kaizu; Y. Okada; S. Tomić
Journal of Renewable Sustainable Energy, 6巻, 1号, 掲載ページ 011206-1-11, 出版日 2014年01月, 査読付
研究論文（学術雑誌）, 英語 - Fabrication of InAs Qantum Dots on Nitrided GaAs (001) Surface
T. Kaizu; T. Kita
13th International Symposium on Advanced Fluid Information, 掲載ページ 102-103, 出版日 2013年11月
研究論文（国際会議プロシーディングス）, 英語 - Quantum size effects in GaAs nanodisks fabricated using a combination of the bio-template technique and neutral beam etching
Yosuke Tamura; Toshiyuki Kaizu; Takayuki Kiba; Makoto Igarashi; Rikako Tsukamoto; Akio Higo; Weiguo Hu; Cedric Thomas; Mohd Erman Fauzi; Takuya Hoshii; Ichiro Yamashita; Yoshitaka Okada; Akihiro Murayama; Seiji Samukawa
Nanotechnology, 24巻, 28号, 掲載ページ 285301-1-6, 出版日 2013年07月19日, 査読付, We successfully fabricated defect-free, distributed and sub-20-nm GaAs quantum dots (named GaAs nanodisks (NDs)) by using a novel top-down technique that combines a new bio-template (PEGylated ferritin) and defect-free neutral beam etching (NBE). Greater flexibility was achieved when engineering the quantum levels of ND structures resulted in greater flexibility than that for a conventional quantum dot structure because structures enabled independent control of thickness and diameter parameters. The ND height was controlled by adjusting the deposition thickness, while the ND diameter was controlled by adjusting the hydrogen-radical treatment conditions prior to NBE. Photoluminescence emission due to carrier recombination between the ground states of GaAs NDs was observed, which showed that the emission energy shift depended on the ND diameters. Quantum level engineering due to both diameter and thickness was verified from the good agreement between the PL emission energy and the calculated quantum confinement energy. © 2013 IOP Publishing Ltd.
研究論文（学術雑誌）, 英語 - Application of photoreflectance to advanced multilayer structures for photovoltaics
D. F. Marron; E. Canovas; I. Artacho; C. R. Stanley; M. Steer; T. Kaizu; Y. Shoji; N. Ahsan; Y. Okada; E. Barrigon; I. Rey-Stolle; C. Algora; A. Marti; A. Luque
Materials Science and Engineering B, 178巻, 9号, 掲載ページ 599-608, 出版日 2013年05月, 査読付
研究論文（学術雑誌）, 英語 - Photoluminescence from GaAs nanodisks fabricated by using combination of neutral beam etching and atomic hydrogen-assisted molecular beam epitaxy regrowth
Toshiyuki Kaizu; Yosuke Tamura; Makoto Igarashi; Weiguo Hu; Rikako Tsukamoto; Ichiro Yamashita; Seiji Samukawa; Yoshitaka Okada
筆頭著者, Applied Physics Letters, AMER INST PHYSICS, 101巻, 11号, 掲載ページ 113108-1-4, 出版日 2012年09月, 査読付, We have fabricated GaAs nanodisk (ND) structures by using a combination of neutral beam etching process and atomic hydrogen-assisted molecular beam epitaxy regrowth. We have observed clear photoluminescence (PL) emissions from GaAs NDs. The peak energy showed a blueshift due to the quantum confinement in three spatial dimensions, and it agreed with the theoretically estimated transition energy. The PL results also showed that the cap-layer disks act as radiative recombination centers. We have confirmed that the PL emission originates from the GaAs NDs, and our approach is effective for the fabrication of high quality ND structures. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752233]
研究論文（学術雑誌）, 英語 - High-density and Sub-20-nm GaAs Nanodisk Array Fabricated Using Neutral Beam Etching Process for High Performance QDs Devices
Yosuke Tamura; Makoto Igarashi; Mohd Erman Fauzi; Rikako Tsukamoto; Toshiyuki Kaizu; Takayuki Kiba; Ichiro Yamashita; Yoshitaka Okada; Akihiro Murayama; Seiji Samukawa
2012 12TH IEEE CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO), IEEE, 出版日 2012年, III-V compound quantum dots are extremely attractive in researching the quantum effect and developing future quantum photovoltaic devices. We developed a defect-free fabrication process for sub-20-nm gallium arsenide (GaAs) nanodisk using bio-template and neutral beam etching. We successfully fabricated defect-free and high-aspect ratio GaAs/aluminium gallium arsenide (AIGaAs) stack-layered sub-20-nm nanodisk structures. The diameter of the GaAs nanodisk could be precisely controlled from 12 to 18 nm by a combination of Hydrogen-radical treatment and neutral beam etching. We then detected a strong photoluminescence peak originating from the GaAs nanodisk for the first time even when using top-down processes. We found that our fabricated nanodisk array structures have great potential for high performance III-V compound optical quantum dots devices.
研究論文（国際会議プロシーディングス）, 英語 - Optical absorption, photo-luminescence and miniband formation of a highly ordered and dense 2-dimensional array of Si nanodisks for quantum dot solar cells
Makoto Igarashi; Chi-Hsien Huang; Xuan-Yu Wang; Mohd Fairuz Budiman; Yosuke Tamura; Takayuki Kiba; Akihiro Murayama; Toshiyuki Kaizu; Yoshitaka Okada; Seiji Samukawa
Conference Record of the IEEE Photovoltaic Specialists Conference, 掲載ページ 003511-003515, 出版日 2011年, We fabricated a highly ordered and dense 2-dimensional array of Si nanodisks (NDs) with our new processes using a bio-template and damage-free neutral beam. Direct-bandgap-like photon emissions were observed from the Si-NDs due to quantum confinement by using time resolved PL measurements. The PL time-profiles were identified in three components (nanosecond region or less) originated in lateral coupling of wave-function i.e. miniband state and localized state in silicon nanodisks. Furthermore, The I-V characteristics of the 2D array of Si-NDs using conductive atomic force microscopy (AFM) indicated that the electronic states of the neighboring NDs were coupled and formed minibands in the 2D array. We also fabricated Si-NDs with an inter-layer of SiC, and found that the SiC matrix could yield a high absorption coefficient without any shift in the bandgap energy (Eg) of the Si-ND structure. © 2011 IEEE.
研究論文（国際会議プロシーディングス）, 英語 - Damage-free top-down processes for fabricating two-dimensional array of sub-10-nanometer GaAs nanodiscs using bio-template and neutral beam etching for intermediate band solar cell applications
Mohd Fairuz Budiman; Xuan-Yu Wang; Chi-Hsien Huang; Rikako Tsukamoto; Toshiyuki Kaizu; Makoto Igarashi; Pierre-Andre Mortemousque; Yoshitaka Okada; Akihiro Murayama; Kohei M. Itoh; Yuzo Ohno; Seiji Samukawa
Conference Record of the IEEE Photovoltaic Specialists Conference, 掲載ページ 002675-002678, 出版日 2011年, A series of damage-free fabrication processes for a two-dimensional array of sub-10-nm GaAs nanodiscs was developed by using bio-templates and neutral beam etching. The photoluminescence of GaAs etched with a neutral beam clearly revealed that the processes could accomplish defect-free etching for GaAs. In the bio-template process, a hydrogen-radical treatment was used to remove the native oxide on the GaAs surface, and then neutral beam oxidation (NBO) was used to form a hydrophilic 1-nm-thick GaAs oxide (GaAs-NBO) film. The two-dimensional array of ferritins (protein including a 7-nm-diameter iron core) can be arranged well on hydrophilic GaAs-NBO film. The ferritin protein shell was removed using an oxygen-radical treatment at a low temperature of 280°C without thermal damage to the GaAs. Then, the neutral beam etched the the GaAs to form defect-free nanodisc structure of using the iron core as an etching mask. Finally, the iron oxide core was removed by wet etching with diluted hydrogen chloride and the fabrication process was completed without inflicting any damage to the GaAs. As a result, a two-dimensional array of GaAs quantum dots with a diameter of ∼7 nm, a height of ∼10 nm, a high taper angle of 88°, and a quantum dot density of more than 7×10 11 cm -2 was successfully fabricated without causing any damage to the GaAs. © 2011 IEEE.
研究論文（国際会議プロシーディングス）, 英語 - Magnetotransport properties of Yb-doped AlxGa1-xAs/GaAs two-dimensional electron systems
Toshiyuki Kaizu; Yasutaka Imanaka; Kanji Takehana; Tadashi Takamasu
筆頭著者, Physica E: Low-dimensional Systems and Nanostructures, ELSEVIER SCIENCE BV, 42巻, 4号, 掲載ページ 1126-1129, 出版日 2010年02月, 査読付, The magnetotransport properties of three different structured Yb-doped AlxGa1-xAs/GaAs twodimensional electron systems (2DES) were investigated. The Al0.3Ga0.7As:Yb sample showed a clear integer quantum Hall effect (IQHF) irrespective of photoexcitation, whereas the AlAs:Yb samples showed a clear IQHE only under photoexcitation above 1.89 eV. Under a dark condition and photoexcitation below 1.89 eV, the resistance of the AlAs:Yb samples significantly increased in the high-magnetic-field region, suggesting that 2D electrons were scattered by the Yb-related electron trap. From the analysis of a band diagram, the Yb-related states in the AlAs:Yb and Al0.3Ga0.7As:Yb samples were estimated to be located below and above the GaAs conduction band edge, respectively, and the level of the Yb-related state was found to shift with the change in the energy band structure of the host material. (C) 2009 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Time-Resolved X-ray Diffraction Measurements of High-Density InAs Quantum Dots on Sb/GaAs Layers and the Suppression of Coalescence by Sb-Irradiated Growth Interruption
Naoki Kakuda; Toshiyuki Kaizu; Masamitu Takahasi; Seiji Fujikawa; Koichi Yamaguchi
Japanese Journal of Applied Physics, JAPAN SOC APPLIED PHYSICS, 49巻, 9号, 掲載ページ 095602-1-4, 出版日 2010年, 査読付, Self-assembly of high-density InAs quantum dots (QDs) on Sb-irradiated GaAs buffer layers was observed in-situ by a time-resolved X-ray diffraction (XRD) technique using a combination of XRD and molecular beam epitaxy. Evolution of dot height and lattice constant was analyzed during InAs QD growth and subsequent growth interruption (GI), and as a result, dislocated giant dots due to coalescence and coherent dots were separately evaluated. An Sb-irradiated GI (Sb-GI) method to be applied after InAs growth was attempted for the suppression of coalescence. Using this method, the XRD intensity of giant dots decreased, and the photoluminescence intensity of InAs QDs was enhanced. High-density InAs QDs without giant dots were produced by using the combination of the QD growth on the Sb-irradiated GaAs buffer layers and the Sb-GI. (C) 2010 The Japan Society of Applied Physics
研究論文（学術雑誌）, 英語 - In situ X-ray diffraction during stacking of InAs/GaAs(001) quantum dot layers and photoluminescence spectroscopy
M. Takahasi; T. Kaizu
Journal of Crystal Growth, ELSEVIER SCIENCE BV, 311巻, 7号, 掲載ページ 1761-1763, 出版日 2009年03月, 査読付, The growth of five layers of InAs quantum dots embedded in GaAs matrices was investigated by in situ synchrotron X-ray diffraction. Time-resolved X-ray diffraction revealed the evolution of the strains and height of quantum dots during the entire growth process including the nucleation of islands and encapsulation with GaAs at various substrate temperatures. Comparisons of in situ X-ray results with postgrowth photoluminescence spectra showed a clear correlation between the structural and optical properties. (C) 2008 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - GaSb(001) Surface Reconstructions Measured at the Growth Front by Surface X-ray Diffraction
B. P. Tinkham; O. Romanyuk; W. Braun; K. H. Ploog; F. Grosse; M. Takahasi; T. Kaizu; J. Mizuki
Journal of Electronic Materials, SPRINGER, 37巻, 12号, 掲載ページ 1793-1798, 出版日 2008年12月, 査読付, Surface x-ray diffraction was employed, in situ, to measure the GaSb(001)-(1 x 5) and (1 x 3) surface phases under technologically relevant growth conditions. We measured a large set of fractional-order in-plane diffraction peaks arising from the superstructure of the surface reconstruction. From the data we calculated two-dimensional (2D) Patterson functions, the peaks of which represent inter-atomic distances weighted by the number of electrons in the individual atoms. For the (1 x 3) phase we obtained good agreement between our data and the beta(4 x 3) model proposed in recent experimental and theoretical work. Our measurements on the Sb-rich (1 x 5) phase provide evidence that the structure under growth conditions is, in fact, different from that of the models previously suggested on the basis of scanning tunneling microscopy (STM). We discuss reasons for this discrepancy as well as the identified structural elements for these reconstructions, which include surface relaxations and subsurface rearrangement.
研究論文（学術雑誌）, 英語 - In situ determination of Sb distribution in Sb/GaAs(001) layer for high-density InAs quantum dot growth
Toshiyuki Kaizu; Masamitu Takahasi; Koichi Yamaguchi; Jun'ichiro Mizuki
筆頭著者, Journal of Crystal Growth, ELSEVIER SCIENCE BV, 310巻, 15号, 掲載ページ 3436-3439, 出版日 2008年07月, 査読付, An Sb-adsorbed GaAs(0 0 1) substrate that serves as a template for high-density InAs quantum dot (QD) growth was investigated using in situ X-ray diffraction. The Sb distribution in the top eight layers from the surface was determined by crystal truncation rod scattering analysis. It was found that Sb atoms penetrated to the eighth layer when GaAs(0 0 1) came in contact with an Sb environment. The amounts of Sb in the first and second layers were, however, saturated at 1/3 atomic layer (AL) and 2/3 AL, respectively. A comparison between the X-ray results and atomic force microscopy observations of the QD density showed that the formation of high-density QDs is correlated with the total amount of Sb in the surface and subsurface layers. (c) 2008 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Modification of InAs quantum dot structure during annealing
Toshiyuki Kaizu; Masamitu Takahasi; Koichi Yamaguchi; Jun'ichiro Mizuki
筆頭著者, Journal of Crystal Growth, ELSEVIER SCIENCE BV, 301-302巻, 掲載ページ 248-251, 出版日 2007年04月, 査読付, The structural modification of InAs/GaAs(0 0 1) quantum dots (QDs) grown with 2.0 or 2.7 monolayers (ML) of InAs during annealing was investigated by a combination of in situ X-ray diffraction (XRD), reflection high-energy electron-beam diffraction (RHEED) and ex situ atomic force microscopy (AFM). For 2.0 ML in coverage, QD size increased due to the incorporation of Ga atoms into the QDs, after which QD ripening occurred. For 2.7 ML in coverage, on the other hand, the change in the strain energy due to enhanced intermixing of In and Ga atoms induced a morphological transition from three dimension (3D) to two dimension (2D). These results yielded some useful information about control of the SK QD structure during growth interruption. (c) 2006 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Study of InAs/GaAs(001) nanoisland growth process by in-situ and real-time X-ray diffraction
Masamitu Takahasi; Toshiyuki Kaizu; Jun'ichiro Mizuki
e-Journal of Surface Science and Nanotechnology, 4巻, 掲載ページ 426-430, 出版日 2006年04月22日, 査読付, A monitoring technique for molecular beam epitaxial growth of InAs/GaAs(001) nanoislands is presented. With the help of a combination of synchrotron radiation and a two-dimensional X-ray detector, X-ray diffraction intensity mappings in the reciprocal space have been measured during growth at a rate of 9.6 s per frame. This method provides information on strain distribution and height of Stranski-Krastanov islands under the in situ condition. Because the use of X-rays is not hindered by ambient pressure, this technique is suitable for industry-oriented applications such as organometallic vapor-phase epitaxy as well. © 2006 The Surface Science Society of Japan.
研究論文（学術雑誌）, 英語 - In situ monitoring of internal strain and height of InAs nanoislands grown on GaAs(001)
M Takahasi; T Kaizu; J Mizuki
Applied Physics Letters, AMER INST PHYSICS, 88巻, 10号, 掲載ページ 101917-1-3, 出版日 2006年03月, 査読付, A monitoring technique for molecular beam epitaxial growth of InAs/GaAs(001) nanoislands is presented. With the help of synchrotron radiation, x-ray diffraction intensity mapping in reciprocal space has been measured during growth. The internal strain distribution and height of the Stranski-Krastanov islands were monitored at a temporal resolution of 9.6 s. The relaxation process of internal strain inside the Stranski-Krastanov islands displayed significant dependence on the growth temperature. (c) 2006 American Institute of Physics.
研究論文（学術雑誌）, 英語 - Controlled stacking growth of uniform InAs quantum dots by molecular beam epitaxy
Y Suzuki; T Kaizu; K Yamaguchi
Physica E: Low-dimensional Systems and Nanostructures, ELSEVIER SCIENCE BV, 21巻, 2-4号, 掲載ページ 555-559, 出版日 2004年03月, 査読付, Double-stacked InAs quantum dots (QDs) were grown by molecular beam epitaxy via Stranski-Krastanov growth mode. Transition of the facet formation from {136} plane to {110} plane was observed during the stacking growth of InAs QDs by reflection high-energy electron-beam diffraction. The enhanced growth rate and the different facet formation in the stacking growth were caused by tensile strain of the GaAs underlying layer. Low arsenic pressure and low growth rate conditions played an important role for a perfect coupling and uniformity in the size of the stacked QDs. The narrow photoluminescence line width of 17.6 meV was successfully obtained from the stacked InAs QDs. (C) 2003 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Self-Formation of Uniform InAs Quantum Dots and Quantum-Dot Chains
K.Yamaguchi; T.Kaizu; T.Kanto; Y.Suzuki
Transactions of the Materials Research Society of Japan, 29巻, 1号, 掲載ページ 117-121, 出版日 2004年01月, 査読付 - Facet formation of uniform InAs quantum dots by molecular beam epitaxy
T Kaizu; K Yamaguchi
筆頭著者, Japanese Journal of Applied Physics, INST PURE APPLIED PHYSICS, 42巻, 6S号, 掲載ページ 4166-4168, 出版日 2003年06月, 査読付, Uniform InAs quantum dots were grown by molecular beam epitaxy via the Stranski-Krastanov (SK) growth mode, and the self-size-limiting effects due to facet formation were investigated. The facet formation of the 3D dots depends on the growth conditions. As the growth rate and the arsenic pressure decrease, the crystal orientation of the facet changes from the {136} plane to the {101} plane. After the self-size-limiting effects due to the facet formation, the surface concentration of indium adatoms increases, and the density of the coalescent dots also increases. The low arsenic pressure and the low growth rate are effective conditions for suppressing the coalescence and reducing the size fluctuation of the coherent 3D dots. As a result, it was found that the uniform formation of the InAs quantum dots can be achieved by conventional SK-mode growth under low growth rate and low arsenic pressure conditions.
研究論文（学術雑誌）, 英語 - Uniform formation of two-dimensional and three-dimensional InAs islands on GaAs by molecular beam epitaxy
T Kaizu; K Yamaguchi
筆頭著者, Japanese Journal of Applied Physics, INST PURE APPLIED PHYSICS, 42巻, 4R号, 掲載ページ 1705-1708, 出版日 2003年04月, 査読付, In order to fabricate uniform InAs quantum dots on a GaAs(001) substrate, the shape transition from two-dimensional (2D) to 3D islands was investigated in the case of molecular beam epitaxy via the Stranski-Krastanov growth mode. A critical lateral size of the 2D islands, just before the 3D formation, depended on the growth conditions.. In case of high growth rate and high arsenic pressure conditions, the critical size became small because of the multi nucleation mode. The stacked 2D islands induced a large fluctuation in the critical lateral size and caused large inhomogeneous broadening in the pyramidal 3D dots, which were covered by the stable facets. Therefore, the low growth rate and the low arsenic; pressure were effective conditions to achieve uniform 2D and 3D islands.
研究論文（学術雑誌）, 英語 - Uniform formation process of self-organized InAs quantum dots
K Yamaguchi; T Kaizu; K Yujobo; Y Saito
Journal of Crystal Growth, ELSEVIER SCIENCE BV, 237-239巻, Part2号, 掲載ページ 1301-1306, 出版日 2002年04月, 査読付, Uniform InAs quantum dots (QDs) were successfully grown by molecular beam epitaxy using the conventional Stranski-Krastanov growth mode. Two self-size-limiting (SSL) behaviors of the island size played an important role in achieving the uniform formation of the InAs QDs. In the initial growth stage of the 2-dimensional (2D) InAs platelets, the compressive strain at the stop edge of the 2D islands induced the first SSL behavior of their lateral size. The growth mode transition from 2D to 3D rapidly occurred around 20 nm in the lateral size. The 3D dots were surrounded by four {1 3 6} facets, which provided the second SSL feature. The uniform InAs QDs, grown through two SSL mechanisms, revealed a narrow photoluminescence linewidth of <20 meV. (C) 2002 Elsevier Science B.V. All rights reserved.
研究論文（学術雑誌）, 英語 - Self size-limiting process of InAs quantum dots grown by molecular beam epitaxy
T Kaizu; K Yamaguchi
筆頭著者, Japanese Journal of Applied Physics, INST PURE APPLIED PHYSICS, 40巻, 3S号, 掲載ページ 1885-1887, 出版日 2001年03月, 査読付, In the molecular beam epitaxy (MBE) growth of InAs quantum dots (QDs), we investigated the dot formation via the self size-limiting process. Accumulation of size-limited InAs QDs resulted in narrow inhomogeneous broadening of photoluminescence (PL) linewidth and low energy shift of PL peak position. Atomic force microscopy (AFM) and reflection high-energy electron-beam diffraction (RHEED) observations revealed the appearance of {136} facets on the side wall of size-limited InAs dots. It was proposed that the facet formation played an important role in the self size-limiting behavior.
研究論文（学術雑誌）, 英語 - Stranski-Krastanov growth of InAs quantum dots with narrow size distribution
K Yamaguchi; K Yujobo; T Kaizu
Japanese Journal of Applied Physics, INST PURE APPLIED PHYSICS, 39巻, 12A号, 掲載ページ L1245-L1248, 出版日 2000年12月, 査読付, Coherently strained InAs quantum dots (QDs) with narrow inhomogeneous broadening were grown by molecular beam epitaxy (MBE) using the Stranski-Krastanov (SK) growth mode. The increase in the InAs dot size and decrease in the dot density were induced by surface migration enhancement due to the low arsenic pressure below 6 x 10(-7) Torr. In addition, the low arsenic pressure and the low growth rate produced the self size-limiting effect, which was attributed to the inhibition of indium incorporation. As a result, the narrowest photoluminescence (PL) linewidth of 18.6 meV (14 K) was successfully obtained from the single InAs/GaAs QD layer.
研究論文（学術雑誌）, 英語
MISC
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出版日 2011年08月16日, 応用物理学会学術講演会講演予稿集(CD-ROM), 72nd巻, 掲載ページ ROMBUNNO.1A-K-5, 日本語, 201102240790914512 - 高密度InAs量子ドットのSb照射成長中断における時間分解X線回折測定(3)
山本和輝; 角田直輝; 海津利行; 海津利行; 高橋正光; 藤川誠司; 山口浩一
出版日 2010年08月30日, 応用物理学会学術講演会講演予稿集(CD-ROM), 71st巻, 掲載ページ ROMBUNNO.14A-ZQ-11, 日本語, 201002227006765642 - シリコン(Si)ナノディスク2次元アレイによる高効率光吸収とバンドギャップエネルギー制御の実現
BIN BUDIMAN Mohd Fairuz; HUANG Chi‐Hsien; HUANG Chi‐Hsien; WANG Uan‐Yu; WANG Uan‐Yu; 海津利行; 海津利行; 五十嵐誠; 五十嵐誠; 大島隆治; 大島隆治; 岡田至崇; 岡田至崇; 山下一郎; 山下一郎; 寒川誠二; 寒川誠二
出版日 2010年08月30日, 応用物理学会学術講演会講演予稿集(CD-ROM), 71st巻, 掲載ページ ROMBUNNO.14P-NC-8, 日本語, 201002257175971754 - 高密度InAs量子ドットのSb照射成長中断における時間分解X線回折測定(2)
角田直輝; 海津利行; 高橋正光; 藤川誠司; 山口浩一
出版日 2009年09月08日, 応用物理学会学術講演会講演予稿集, 70th巻, 1号, 掲載ページ 398, 日本語, 200902238104180998 - Ybドープ2次元電子系におけるYbトラップ準位の考察
海津利行; 高増正; 竹端寛治; 今中康貴
一般社団法人日本物理学会, 出版日 2009年08月18日, 日本物理学会講演概要集, 64巻, 2号, 掲載ページ 591-591, 日本語, 1342-8349, 200902228368832122, 110007498159, AA11439205 - 高密度InAs量子ドットのSb照射成長中断における時間分解X線回折測定
角田直輝; 海津利行; 高橋正光; 藤川誠司; 山口浩一
出版日 2009年03月30日, 応用物理学関係連合講演会講演予稿集, 56th巻, 1号, 掲載ページ 450, 日本語, 200902259682874983 - YbドープAlGaAs/GaAs2次元電子系の電気伝導特性の励起エネルギー依存性
海津利行; 高増正; 竹端寛治; 今中康貴
一般社団法人日本物理学会, 出版日 2009年03月03日, 日本物理学会講演概要集, 64巻, 1号, 掲載ページ 687-687, 日本語, 1342-8349, 200902229140539740, 110007372289, AA11439205 - YbドープAlGaAs/GaAsヘテロ構造の電気伝導特性の磁場依存性
海津利行; 高増正; 竹端寛治; 今中康貴
一般社団法人日本物理学会, 出版日 2008年08月25日, 日本物理学会講演概要集, 63巻, 2号, 掲載ページ 587-587, 日本語, 1342-8349, 200902212701651501, 110006984672, AA11439205 - Ybドープ2次元電子系の強磁場電気伝導特性
高増正; 海津利行; 今中康貴; 竹端寛治
一般社団法人日本物理学会, 出版日 2008年02月29日, 日本物理学会講演概要集, 63巻, 1号, 掲載ページ 682-682, 日本語, 1342-8349, 200902211867472900, 110007195080, AA11439205 - In-situ X-ray diffraction study on structural evolution of InAs islands on GaAs(001) during annealing
Masamitu Takahasi; Toshiyuki Kaizu; Jun'ichiro Mizuki
The evolution of strain inside InAs/GaAs(001) quantum dots during annealing after deposition was studied by in situ grazing-incidence X-ray diffraction. The use of synchrotron radiation and two-dimensional detector enabled measurements at a temporal resolution of 9.6 s. The temperature dependence of the structural change during annealing can be interpreted in terms of the miscibility of InAs and GaAs. © 2007 American Institute of Physics., 出版日 2007年12月01日, AIP Conference Proceedings, 893巻, 掲載ページ 75-76, 0094-243X, 77958515348 - YbドープGaAs/AlGaAsヘテロ構造の発光,輸送特性
高増正; 海津利行; 今中康貴; 竹端寛治
一般社団法人日本物理学会, 出版日 2007年08月21日, 日本物理学会講演概要集, 62巻, 2号, 掲載ページ 682-682, 日本語, 1342-8349, 200902219051471729, 110007142780, AA11439205 - 分子線エピタキシャル法による半導体ナノ構造成長のその場X線回折
高橋正光; 海津利行; 水木純一郎
出版日 2007年03月27日, 応用物理学関係連合講演会講演予稿集, 54th巻, 0号, 掲載ページ 109, 日本語, 200902264153217199 - Sb照射GaAs(001)表面のその場X線回折測定
海津利行; 高橋正光; 菅藤徹; 築地伸和; 外村慎一; 山口浩一; 水木純一郎
出版日 2007年03月27日, 応用物理学関係連合講演会講演予稿集, 54th巻, 1号, 掲載ページ 448, 日本語, 200902283227089745 - リアルタイム計測:半導体ナノドット成長過程における構造変化
高橋正光; 海津利行
出版日 2006年08月29日, 応用物理学会学術講演会講演予稿集, 67th巻, 0号, 掲載ページ 10, 日本語, 200902287441777115 - InAs/GaAs(001)成長のリアルタイムX線回折測定
高橋正光; 海津利行; 水木純一郎
出版日 2006年03月22日, 応用物理学関係連合講演会講演予稿集, 53rd巻, 1号, 掲載ページ 323, 日本語, 200902209194865919 - その場X線回折による成長中継中のInAs量子ドットの構造変化の解析
海津利行; 高橋正光; 佐藤峻之; 堀田正憲; 山口浩一; 水木純一郎
出版日 2005年03月29日, 応用物理学関係連合講演会講演予稿集, 52nd巻, 1号, 掲載ページ 348, 日本語, 200902232994993216 - InAs/GaAs(001)量子ドット成長のリアルタイムX線測定
高橋正光; 海津利行
出版日 2005年03月29日, 応用物理学関係連合講演会講演予稿集, 52nd巻, 0号, 掲載ページ 109, 日本語, 200902239386436015 - 自己制限InAs量子ドットの構造安定性
岩崎誠樹; 海津利行; 山口浩一
出版日 2004年03月28日, 応用物理学関係連合講演会講演予稿集, 51st巻, 1号, 掲載ページ 357, 日本語, 200902224047187998 - 高密度・高均一InAs量子ドットの積層成長
海津利行; 山口浩一
出版日 2003年08月30日, 応用物理学会学術講演会講演予稿集, 64th巻, 1号, 掲載ページ 268, 日本語, 200902297846357941 - GaAs埋め込みInAs量子ドットの1.3μm発光
海津利行; 武田宙; 山口浩一
出版日 2003年08月30日, 応用物理学会学術講演会講演予稿集, 64th巻, 3号, 掲載ページ 1269, 日本語, 200902219115129850 - 自己制限InAs量子ドット形成過程のInAs成長条件依存性 (2)
海津利行; 山口浩一
出版日 2003年03月27日, 応用物理学関係連合講演会講演予稿集, 50th巻, 3号, 掲載ページ 1460, 日本語, 200902262766094690 - 自己制限InAs量子ドット形成過程のInAs成長条件依存性
海津利行; 山口浩一
出版日 2002年09月24日, 応用物理学会学術講演会講演予稿集, 63rd巻, 1号, 掲載ページ 281, 日本語, 200902147688912507 - InAs量子ドットのサイズ自己制限過程
海津利行; 山口浩一
出版日 2002年03月27日, 応用物理学関係連合講演会講演予稿集, 49th巻, 1号, 掲載ページ 336, 日本語, 200902151761920847 - InAs2次元成長層のアニールによる3次元ドット形成
岩崎誠樹; 海津利行; 山口浩一
出版日 2002年03月27日, 応用物理学関係連合講演会講演予稿集, 49th巻, 1号, 掲載ページ 335, 日本語, 200902107441845481 - InAsアイランドサイズの形成位置依存性
海津利行; 山口浩一
出版日 2001年09月11日, 応用物理学会学術講演会講演予稿集, 62nd巻, 1号, 掲載ページ 230, 日本語, 201202105086897494 - 自己組織化InAsドットの初期形成過程
市原純; 海津利行; 山口浩一
出版日 2001年03月28日, 応用物理学関係連合講演会講演予稿集, 48th巻, 3号, 掲載ページ 1345, 日本語, 201202191468317386 - 自己制限InAs量子ドットのファセット形成過程
海津利行; 山口浩一
出版日 2001年03月28日, 応用物理学関係連合講演会講演予稿集, 48th巻, 3号, 掲載ページ 1345, 日本語, 201202155098573217 - Narrow Size Distribution of Facet-Formed InAs Quantum Dots
出版日 2001年, Proceedings of the 6th International Symposium on Advanced Physical Fields 2001, 掲載ページ 330-334 - 自己組織化InAs量子ドットの低成長速度形成
祐乗坊邦彦; 海津利行; 山口浩一
出版日 2000年09月03日, 応用物理学会学術講演会講演予稿集, 61st巻, 1号, 掲載ページ 252, 日本語, 201202184180522159 - 自己制限InAs量子ドットの形成過程
海津利行; 山口浩一
出版日 2000年09月03日, 応用物理学会学術講演会講演予稿集, 61st巻, 3号, 掲載ページ 1150, 日本語, 201202164240085470 - 自己組織化InAs量子ドットの高均一化 ドットサイズの自己制限効果
山口浩一; 海津利行; 祐乗坊邦彦
Straski-Krastanov成長モードの自己組織化InAs量子ドットの作製において, InAs成長量に依存しないドットサイズの自己制限効果が観察され, フォトルミネッセンス(PL)半値幅21.3meVの高均一なドットサイズ分布を達成した.この自己制限機構としては, 安定なファセット面の形成によるものと考察された.PL強度の温度依存性より, 異なるサイズを有するInAs量子ドット間で電子の熱的放出と取り込み過程が起こり, 見かけ上PL半値幅に温度依存性が見られないことを示した.低As圧成長では, コヒーレントドットの自己制限サイズが大きくなり, またコアレッセンス化が抑制されることが分かった., 一般社団法人電子情報通信学会, 出版日 2000年06月21日, 電子情報通信学会技術研究報告, 100巻, 115(LQE2000 14-25)号, 掲載ページ 13-20, 日本語, 0913-5685, 200902126606698149, 110003308075, AN10442705 - 自己組織化InAs量子ドットの低As圧成長
祐乗坊邦彦; 海津利行; 山口浩一
出版日 2000年03月28日, 応用物理学関係連合講演会講演予稿集, 47th巻, 1号, 掲載ページ 324, 日本語, 201202151984262880 - 自己組織化InAs量子ドットサイズの自己制限効果(2)
海津利行; 祐乗坊邦彦; 山口浩一
出版日 2000年03月28日, 応用物理学関係連合講演会講演予稿集, 47th巻, 1号, 掲載ページ 486, 日本語, 201202197495067446 - 自己組織化InAs量子ドットサイズの自己制限効果
海津利行; 山口浩一
出版日 1999年09月01日, 応用物理学会学術講演会講演予稿集, 60th巻, 1号, 掲載ページ 393, 日本語, 200902122007669224 - 高均一InAs自己形成量子ドットの発光特性
海津利行; 寺沢博雅; 山口浩一
出版日 1999年03月28日, 応用物理学関係連合講演会講演予稿集, 46th巻, 1号, 掲載ページ 540, 日本語, 200902111138872155
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開催期間 2025年03月14日- 2025年03月17日 - Si基板上のInAsナノワイヤーからの横方向成長によるInAs薄膜成長
アチャリヤ淳一; 海津利行; 宮下 直也; 山口 浩一
口頭発表（一般）, 日本語, 第72回応用物理学会春季学術講演会, 国内会議
発表日 2025年03月16日
開催期間 2025年03月14日- 2025年03月17日 - InAs量子ドット成長に起因する格子不整合歪みを利用した差周波混合によるテラヘルツ電磁波発生
鈴木崇斗; 小島磨; 海津利行; 和田修; 喜多隆
口頭発表（一般）, 日本語, 第85回応用物理学会秋季学術講演会, 国内会議
発表日 2024年09月16日
開催期間 2024年09月16日- 2024年09月20日 - 多重積層InAs/ GaAs量子ドットを用いた光伝導アンテナの様々な励起光波長における光電流の励起光強度依存性
海津利行; 小島磨; 南康夫; 北田貴弘; 原田幸弘; 喜多隆; 和田修
口頭発表（一般）, 日本語, 第85回応用物理学会秋季学術講演会, 国内会議
発表日 2024年09月16日
開催期間 2024年09月16日- 2024年09月20日 - Lateral Photoconductivity of Multiple-Stacked InAs/GaAs Quantum Dot Structure for Photoconductive Antenna Device
T. Kaizu; I. Kohama; Y. Minami; T. Kitada; Y. Harada; O. Kojima; T. Kita; O. Wada
口頭発表（一般）, 英語, Compund Semiconductor Week 2021, 国際会議
発表日 2021年05月12日
開催期間 2021年05月09日- 2021年05月13日 - 光伝導アンテナ応用へ向けた多重積層InAs/GaAs量子ドットの電気特性評価
南康夫; 新免歩; 北田 貴弘; 原田幸弘; 海津利行; 小島磨; 喜多隆; 和田修
ポスター発表, 日本語, 第68回応用物理学会春季学術講演会, 国内会議
発表日 2021年03月19日
開催期間 2021年03月16日- 2021年03月19日 - 光伝導アンテナ応用へ向けた多重積層InAs/GaAs量子ドットの光学特性評価
海津利行; 小濱一晟; 南康夫; 北田貴弘; 原田幸弘; 小島磨; 喜多隆; 和田修
日本語, 第68回応用物理学会春季学術講演会, 国内会議
発表日 2021年03月19日
開催期間 2021年03月16日- 2021年03月19日 - Polarization-Insensitive Optical Gain of Highly stacked InAs/GaAs Quantum Dot Semiconductor Optical Amplifier
T. Kaizu; T. Kakutani; T. Kita
口頭発表（一般）, 英語, SmiconNano2019, Kobe, 日本国, 国際会議
発表日 2019年09月25日
開催期間 2019年09月24日- 2019年09月27日 - One-Dimensional Electronic States in Highly-Stacked InAs/GaAs Quantum Dot Superlattices
T. Kaizu; T. Kita
口頭発表（一般）, 英語, Compound Semiconductor Week 2019, Nara, 国際会議
発表日 2019年05月 - 近接積層InAs/GaAs量子ドット超格子の1次元電子状態の測定温度依存性
海津利行; 喜多隆
口頭発表（一般）, 日本語, 第66回応用物理学会春季学術講演, 国内会議
発表日 2019年03月11日
開催期間 2019年03月09日- 2019年03月12日 - “Effects of GaAs-Capping Temperature on The Emission Wavelength of InAs Quantum Dots Grown on Nitrogen-Doped GaAs(001)Surfaces
N. Uenishi; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 20th International Conference on Molecular Beam Epitaxy, China, 国際会議
発表日 2018年09月 - 多孔質炭素電極を用いた光化学電池の基礎特性
榎本 雅仁; 若木 大智; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 平成30年度半導体エレクトロニクス部門委員会第1回研究会, 奈良先端科学技術大学院大学, 国内会議
発表日 2018年07月 - Carrier Collection Efficiency of Intraband-Excited Carriers in Two-Step Photon Up-Conversion Solar Cells
S. Asahi; K. Nishimura; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 7th edition of the World Conference on Photovoltaic Energy Conversion, Hawaii, 国際会議
発表日 2018年06月 - Multiple Stacking of Capping Temperature-Controlled InAs/GaAs Quantum Dots with AlGaAs Barrier Layers for Broadband Emission
T. Kaizu; T. Koike; T. Kita
口頭発表（一般）, 英語, Compound Semiconductor Week 2018, Cambridge, MA, USA, 国際会議
発表日 2018年05月 - One-Dimensional Electronic States in Closely Stacked InAs/GaAs Quantum Dots with Different Growth Temperatures
T. Kaizu; K. Hirao; T. Kita
口頭発表（一般）, 英語, International Conference on Nanophotonics and Nano-optoelectronics 2018, Yokohama, 国際会議
発表日 2018年04月 - Extraction Efficiency of Up-Converted Electrons in Two-Step Photon Up-Conversion Solar Cells
S. Asahi; K. Nishimura; T. Kaizu; T. Kita
口頭発表（一般）, 英語, International Conference on Nanophotonics and Nano-optoelectronics 2018, Yokohama, 国際会議
発表日 2018年04月 - Two-Step Photo-Excitated Electrons with Extremely-Long Lifetime in Intermedeate-band Solar Cells Using Dot-in Well Strucyure
S. Asahi; H. Teranishi; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 27th Photovoltaic Science and Engineering Conference, Otsu, 国際会議
発表日 2017年11月 - Infrared Absorption Characteristics in Two-Step Photon Up-Conversion Solar Cells
K. Kusaki; S. Asahi; T. Kaizu; R. Tamaki; Y. Okada; T. Kita
口頭発表（一般）, 英語, 27th Photovoltaic Science and Engineering Conference, Otsu, 国際会議
発表日 2017年11月 - Efficient Two-Step Photocurrent in Intermediate Band Solar Cells Using Highly Homogeneous InAs/GaAs Quantum-Dot Superlattice
K. Hirao; S. Asahi; T. Kaizu; Y. Harada; T. Kita
口頭発表（一般）, 英語, 27th Photovoltaic Science and Engineering Conference, Otsu, 国際会議
発表日 2017年11月 - One-Dimensional Miniband Formation in InAs/GaAs Quantum Dot Superlattice
T. Kaizu; T. Kita
口頭発表（一般）, 英語, International Symposium on Novel Energy Nanomaterials, Catalysts and Surfaces for Future Earth -Material Research, Characterization and Imaging by In situ/Operando XAFS and X-ray Techniques-, Tokyo, 国際会議
発表日 2017年10月 - Laser-induced Hydrogen Production Using Porous Carbon
M. Enomoto; Y. Kawajiri; T. Kaizu; T. Uchino; Y. Ichihashi; K. Taniya; S. Nishiyama; M. Mizuhata; M. Sugiyama; M. Ueno; T. Kita
口頭発表（一般）, 英語, International Symposium on Novel Energy Nanomaterials, Catalysts and Surfaces for Future Earth -Material Research, Characterization and Imaging by In situ/Operando XAFS and X-ray Techniques-, Tokyo, 国際会議
発表日 2017年10月 - 低温キャップInAs/GaAs量子ドット超格子中間バンド型太陽電池における熱脱出の抑制
平尾 和輝; 朝日 重雄; 海津 利行; 原田 幸弘; 喜多 隆
口頭発表（一般）, 日本語, 第78回応用物理学会秋季学術講演会, 国内会議
発表日 2017年09月 - 低温キャップInAs/GaAs量子ドット超格子中間バンド型太陽電池における2段階光吸収の増強
平尾 和輝; 朝日 重雄; 海津 利行; 原田 幸弘; 喜多 隆
口頭発表（一般）, 日本語, 日本材料学会半導体エレクトロニクス部門委員会平成29年度第1回研究会, 国内会議
発表日 2017年09月 - Photon Up-Converted Photocurrent in a Single Junction Solar Cell with a Hetero-Interface
K. Kusaki; S. Asahi; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 33rd European Photovoltaic Solar Energy Conference and Exhibition, Netherlands, 国際会議
発表日 2017年09月 - Increasing Photovoltage Boosted by Photon Up-Conversion in a Single-Junction Solar Cell with a Hetero-Interface
S. Asahi; K. Kusaki; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 33rd European Photovoltaic Solar Energy Conference and Exhibition, Netherlands, 国際会議
発表日 2017年09月 - Extended Optical Response of Two-Step Photoexcitation in InAs/GaAs Quantum-Dot Superlattice Intermediate Band Solar Cells
K. Hirao; S. Asahi; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 33rd European Photovoltaic Solar Energy Conference and Exhibition, Netherlands, 国際会議
発表日 2017年09月 - Stokes and Anti-Stokes Photoluminescence in Nitrogen ð-Doped Layer in GaAs
Y. Harada; Y. Ogawa; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 29th International Conference on Defects in Semiconductors, Matsue, 国際会議
発表日 2017年07月 - Increasing Current Generation by Photon Up-Conversion in a Single-Junction Solar Cell with a Hetero-Interface
S. Asahi; K. Kusaki; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 2017 IEEE Photovoltaic Specialists Conference, Washington D.C., 国際会議
発表日 2017年06月 - Broadband Control of Polarization Characteristics in Closely-Stacked InAs/GaAs Quantum Dots
T. Kaizu; Y. Tajiri; T. Kita
口頭発表（一般）, 英語, Compound Semiconductor Week 2017, Berlin, 国際会議
発表日 2017年05月 - GaAs中のエピタキシャル窒素膜における反ストークス発光
原田 幸弘; 小川 泰弘; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第64回応用物理学会春季学術講演会, 国内会議
発表日 2017年03月 - GaAs中のデルタドーピング窒化層を利用した光によるフォノン制御
小川 泰弘; 原田 幸弘; 海津 利行; 喜多 隆
ポスター発表, 日本語, 第27回光物性研究会, 国内会議
発表日 2016年12月 - Two-dimensional delocalized electronic states of epitaxial N d-doped layer in GaAs
Y. Harada; Y. Ogawa; T. Kaizu; T. Kita
口頭発表（招待・特別）, 英語, Energy, Materials, and Nanotechnology Meeting on Epitaxy, 招待, 国際会議
発表日 2016年09月 - InAs/GaAs量子ドット中間バンド型太陽電池における電子の熱脱出過程の解明
平尾 和輝; 渡辺 翔; 朝日 重雄; 海津 利行; 原田 幸弘; 喜多 隆
口頭発表（一般）, 日本語, 第77回応用物理学会秋季学術講演会, 国内会議
発表日 2016年09月 - Control In-Ga Intermixing in InAs Quantum Dot on Nitrogen δ-Doped GaAs
T. Kaizu; T. Kita
口頭発表（一般）, 英語, 19th International Conference on Molecular-Beam Epitaxy, Montpellier, 国際会議
発表日 2016年09月 - Spatial Electronic Structure of an Isovalent Nitrogen Center in GaAs
R. Plantenga; V. Kortan; T. Kaizu; Y. Harada; T. Kita; M. Flatte; P. Koenraad
口頭発表（一般）, 英語, 33rd International Conference on the Physics of Semiconductors, Beijing, 国際会議
発表日 2016年08月 - Thermal carrier-escape process from the intermediate band in InAs/GaAs quantum dot solar cells
K. Hirao; S. Asahi; S. Watanabe; T. Kaizu; Y. Harada; T. Kita
ポスター発表, 日本語, 第35回電子材料シンポジウム, 国内会議
発表日 2016年07月 - Two-Dimensional Energy Dispersion in Thermally Annealed Epitaxial Nitrogen Atomic Sheet in GaAs
Y. Ogawa; Y. Harada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 2016 Compound Semiconductor Week, Toyama, 国際会議
発表日 2016年06月 - Polarization Anisotropy of Electroluminescence and Net-Modal Gain in Highly Stacked InAs/GaAs Quantum-Dot Laser Devices
T. Kaizu; M. Suwa; T. Andachi; Y. Harada; T. Kita
口頭発表（一般）, 英語, 2016 Compound Semiconductor Week, Toyama, 国際会議
発表日 2016年06月 - GaAs First-Spacer-Layer Thickness Dependence of Polarized Photoluminescence Properties of Closely-Stacked InAs/GaAs Quantum Dots with Long-Wavelength Emission
Y. Tajiri; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 2016 Compound Semiconductor Week, Toyama, 国際会議
発表日 2016年06月 - Extended Electron Lifetime in Intermediate-Band Solar Cells Using Dot-in-Well Structure
S. Asahi; H. Teranishi; S. Watanabe; T. Kada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 32nd European Photovoltaic Solar Energy Conference and Exhibition, Munich, 国際会議
発表日 2016年06月 - Enhancement of Two-Step Photon Absorption Due to Miniband Formation in InAs/GaAs Quantum Dot Superlattice Solar Cell
S. Watanabe; S. Asahi; T. Kada; T. Kaizu; Y. Harada; T. Kita
口頭発表（一般）, 英語, 32nd European Photovoltaic Solar Energy Conference and Exhibition, Munich, 国際会議
発表日 2016年06月 - 急速熱アニールしたGaAs中のエピタキシャル窒素膜の輻射再結合寿命
小川 泰弘; 原田 幸弘; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第63回応用物理学会春季学術講演会, 国内会議
発表日 2016年03月 - Time-Resolved Photoluminescence of Thermally-Annealed Nitrogen Atomic Sheet in GaAs
Y. Ogawa; Y. Harada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 17th International Conference on Physics of Light-Matter Coupling in Nanostructures, Nara, 国際会議
発表日 2016年03月 - Polarized Photoluminescence Properties of Closely-Stacked InAs/GaAs Quantum Dots with Long-Wavelength Emission
T. Kaizu; Y. Tajiri; T. Kita
口頭発表（一般）, 英語, 17th International Conference on Physics of Light-Matter Coupling in Nanostructures, Nara, 国際会議
発表日 2016年03月 - InAs/GaAs量子ドット超格子太陽電池におけるミニバンド形成が2段階光吸収に与える影響
渡辺 翔; 朝日 重雄; 加田 智之; 海津 利行; 原田 幸弘; 喜多 隆
口頭発表（一般）, 日本語, 第63回応用物理学会春季学術講演会, 国内会議
発表日 2016年03月 - Extremely Long Carrier Lifetime Due to Electron-Hole Separation in Quantum-Dot Intermediate-Band Solar Cells
S. Asahi; H. Teranishi; T. Kada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 17th International Conference on Physics of Light-Matter Coupling in Nanostructures, Nara, 国際会議
発表日 2016年03月 - InAs/GaAs量子ドット超格子を利用したホットキャリア型太陽電池
渡部 大樹; 原田 幸弘; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第76回応用物理学会秋季学術講演会, 国内会議
発表日 2015年09月 - Epitaxial Nitrogen Atomic Sheet in GaAs Grown by Nitorogen δ-Doping Technique
Y. Harada; T. Baba; Y. Ogawa; T. Kaizu; T. Kita
口頭発表（招待・特別）, 英語, 5th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 招待, Taiwan, 国際会議
発表日 2015年09月 - 急速熱アニールによるGaAs中のエピタキシャル窒素シートにおける2次元物性の制御
小川 泰弘; 原田 幸弘; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 日本材料学会半導体エレクトロニクス部門委員会平成27年度第1回研究会, 国内会議
発表日 2015年07月 - Enhancement of Two Dimensionality in Epitaxial Nitrogen Atomic Sheet in GaAs by Rapid Thermal Annealing
Y. Harada; Y. Ogawa; T. Baba; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 21st International Conference on Electronic Properties of Two-Dimensional Systems/17th International Conference on Modulated Semiconductor Structures, Sendai, 国際会議
発表日 2015年07月 - Broadband Control of Emission Wavelength of InAs/GaAs Quantum Dots by Growth Temperature GaAs Capping Layer
T. Kaizu; T. Matsumura; T. Kita
口頭発表（一般）, 英語, 21st International Conference on Electronic Properties of Two-Dimensional Systems/17th International Conference on Modulated Semiconductor Structures, Sendai, 国際会議
発表日 2015年07月 - Annealing effects on the delocalized electronic states of epitaxial two-dimensional nitrogen atomic sheet in GaAs
Y. Ogawa; Y. Harada; T. Baba; T. Kaizu; T. Kita
ポスター発表, 日本語, 34th Electronic Materials Symposium, 国内会議
発表日 2015年07月 - Two-Step Photocarrier Generation in InAs/GaAs Quantum Dot Superlattice Intermediate Band Solar Cell
T. Kada; T. Tanibuchi; S. Asahi; T. Kaizu; Y. Harada; T. Kita; R. Tamaki; Y. Okada; K. Miyano
口頭発表（一般）, 英語, 42nd IEEE Photovoltaic Specialists Conference, New Orleans, 国際会議
発表日 2015年06月 - Saturable Two-Step Photocurrent Generation in Intermediate-Band Solar Cells Including InAs Quantum Dots Embedded in Al0.3Ga0.7As/GaAs Quantum Wells
S. Asahi; H. Teranishi; N. Kasamatsu; T. Kada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 42nd IEEE Photovoltaic Specialists Conference, New Orleans, 国際会議
発表日 2015年06月 - GaAs中のエピタキシャル二次元窒素膜におけるアニール効果
原田 幸弘; 小川 泰弘; 馬場 健; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第62回応用物理学会春季学術講演会, 国内会議
発表日 2015年03月 - GaAs中のエピタキシャル2次元窒素シート非局在電子状態の発光ダイナミクス
馬場 健; 原田 幸弘; 海津 利行; 喜多 隆
ポスター発表, 日本語, 第24回光物性研究会, 国内会議
発表日 2014年12月 - Two-dimensional electronic states of epitaxial nitrogen atomic sheet in GaAs
Y. Harada; T. Baba; T. Kaizu; T. Kita
口頭発表（招待・特別）, 英語, International Symposium on Recent Progress of Photonic Devices and Materials, 招待, 国際会議
発表日 2014年11月 - Suppression of Thermal Carrier Escape and Efficient Photo-Carrier Generation by Two-Step Photon Absorption in Intermediate-Band Solar Cells Using a Dot-in-Well Structure
S. Asahi; H. Teranishi; N. Kasamatsu; T. Kada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, 6th World Conference on Photovoltaic Energy Conversion, Kyoto International Conference Center, 国際会議
発表日 2014年11月 - Photoluminescence Decay Dynamics in Epitaxial Two-Dimensional Nitrogen Atomic Sheet in GaAs
T. Baba; Y. Harada; T. Kaizu; T. Kita
口頭発表（一般）, 英語, International Symposium on Recent Progress of Photonic Devices and Materials, Kobe University, 国際会議
発表日 2014年11月 - Modulation of Photoluminescence Properties of InAs Quantum Dots on Nitrogen δ-Doped GaAs
T. Kaizu; T. Kita
口頭発表（一般）, 英語, International Symposium on Recent Progress of Photonic Devices and Materials, Kobe University, 国際会議
発表日 2014年11月 - Photoluminescence Properties of InAs Quantum Dots on Nitrogen δ-Doped GaAs
T. Kaizu; T. Kita
口頭発表（一般）, 英語, Eleventh International Conference on Flow Dynamics, Sendai, 国際会議
発表日 2014年10月 - GaAs中のエピタキシャル二次元窒素膜の電子状態 (II)
原田 幸弘; 馬場 健; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第75回応用物理学会学術講演会, 国内会議
発表日 2014年09月 - GaAs中のエピタキシャル二次元窒素膜における発光ダイナミクス
馬場 健; 原田 幸弘; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第75回応用物理学会学術講演会, 国内会議
発表日 2014年09月 - Enhancement of interaction among nitrogen pair centers in epitaxial two-dimensional nitrogen atomic sheet in GaAs
T. Baba; Y. Harada; T. Kaizu; T. Kita
ポスター発表, 日本語, 33rd Electronic Materials Symposium, 国内会議
発表日 2014年07月 - Structural Modification of InAs Quantum Dots Grown on Nitrided GaAs(001)Surface
T. Kaizu; K. Taguchi; T. Kita
ポスター発表, 英語, 8th International Conference on Quantum Dots, Pisa, 国際会議
発表日 2014年05月 - 窒素δドープGaAs(001)層上のInAs量子ドット自己形成
海津 利行; 田口 航平; 喜多 隆
口頭発表（一般）, 日本語, 第61回応用物理学会春季学術講演会, 応用物理学会, 神奈川, 国内会議
発表日 2014年03月 - InAs/GaAs量子ドット太陽電池の量子準位を介した２段階光吸収
加田 智之; 朝日 重雄; 海津 利行; 喜多 隆; 玉置 亮; 宮野 健次郎; 岡田 至崇
口頭発表（一般）, 日本語, 第61回応用物理学会春季学術講演会, 応用物理学会, 神奈川, 国内会議
発表日 2014年03月 - InAs/AlxGa1-xAs量子ドットにおけるキャリアの熱活性特性
朝日 重雄; 寺西 陽之; 笠松 直史; 加田 智之; 海津 利行; 喜多 隆
口頭発表（一般）, 日本語, 第61回応用物理学会春季学術講演会, 応用物理学会, 神奈川, 国内会議
発表日 2014年03月 - Fabrication of InAs Quantum Dots on Nitrided GaAs (001) Surface
T. Kaizu; T. Kita
口頭発表（一般）, 英語, 10th International Conference on Flow Dynamics, Sendai International Center, 国際会議
発表日 2013年11月 - Photoluminescence Properties of Height-controlled GaAs Nanodisks Fabricated by Neutral Beam Etching
T. Kaizu; Y. Tamura; M. Igarashi; W. Hu; C. Thomas; S. Samukawa; Y. Okada
ポスター発表, 英語, 40th International Symposium on Compound Semiconductors, Kobe, 国際会議
発表日 2013年05月 - 中性粒子ビームエッチングにより作製したGaAsナノディスクのPL特性のディスク高さ依存性
海津 利行; 田村 洋典; 五十嵐 誠; トーマス セドリック; 胡 衛国; 寒川 誠二; 岡田 至崇
ポスター発表, 日本語, 第60回応用物理学会春季学術講演会, 応用物理学会, 神奈川, 国内会議
発表日 2013年03月 - トップダウン加工GaAsナノディスクにおけるキャリアスピン緩和
木場 隆之; 須崎 健太; 田村 洋典; 五十嵐 誠; セドリック トーマス; 胡 衛国; 海津 利行; 岡田 至崇; 寒川 誠二; 村山 明宏
口頭発表（一般）, 日本語, 第60回応用物理学会春季学術講演会, 応用物理学会, 神奈川, 国内会議
発表日 2013年03月 - 単層InAs/GaAs量子ドット構造のDLTS評価
中野 廣一; 海津 利行; 星井 拓也; 岡田至崇
口頭発表（一般）, 日本語, 秋季第73回応用物理学会学術講演会, 応用物理学会, 愛媛, 国内会議
発表日 2012年09月 - 原子状水素援用MBEによる2次元GaAsナノディスクアレイのGaAs/AlGaAsキャップ層再成長
海津 利行; 田村 洋典; 五十嵐 誠; 胡 衛国; 寒川 誠二; 岡田 至崇
口頭発表（一般）, 日本語, 秋季第73回応用物理学会学術講演会, 応用物理学会, 愛媛, 国内会議
発表日 2012年09月 - バイオテンプレート極限加工によるGaAsナノディスクの作製と発光特性
田村 洋典; 五十嵐 誠; トーマス セドリック; モハマド エルマン ファウジ; 胡 衛国; 塚本 里加子; 海津 利行; 星井 拓也; 木場 隆之; 山下 一郎; 岡田 至崇; 村山 明宏; 寒川 誠二
口頭発表（一般）, 日本語, 秋季第73回応用物理学会学術講演会, 応用物理学会, 愛媛, 国内会議
発表日 2012年09月 - Observation of photo- luminescence from 2-dimentional GaAs nanodisk array regrown by atomic hydrogen-assisted molecular beam epitaxy
T. Kaizu; Y. Tamura; M. Igarashi; W. Hu; R. Tsukamoto; I. Yamashita; S. Samukawa; Y. Okada
口頭発表（一般）, 英語, 17th International Conference on Molecular Beam Epitaxy, Nara, 国際会議
発表日 2012年09月 - 2次元Siナノディスクアレイにおけるミニバンド形成と電気伝導性の向上
モハマド エルマン ファウジ; 五十嵐 誠; 胡 衛国; 海津 利行; 岡田 至崇; 寒川 誠二
口頭発表（一般）, 日本語, 秋季第73回応用物理学学術講演会, 応用物理学, 愛媛, 国内会議
発表日 2012年09月 - High-density and Sub-20-nm GaAs Nanodisk Array Fabricated Using Neutral Beam Etching Process for High Performance QDs Devices
Y. Tamura; M. Igarashi; M. E. Fauzi; R. Tsukamoto; T. Kaizu; T. Kiba; I. Yamashita; Y. Okada; A. Murayama; S. Samukawa
口頭発表（一般）, 英語, 12th International Conference on Nanotechnology, United Kingdom, 国際会議
発表日 2012年08月 - バイオテンプレート極限加工によるGaAs 量子ナノディスク構造の制御
田村 洋典; 五十嵐 誠; モハマド エルマン ファウジ; 胡 衛国; 海津 利行; 岡田 至崇; 寒川 誠二
口頭発表（一般）, 日本語, 春季第59回応用物理学会関係連合講演会, 応用物理学会, 東京, 国内会議
発表日 2012年03月 - 障壁材料としてSiCを用いたSi量子ナノディスクアレイ構造の電気・光学特性
五十嵐 誠; 海津 利行; 岡田 至崇; 木場 隆之; 村山 明宏; 寒川 誠二
口頭発表（一般）, 日本語, 秋季第72回応用物理学会学術講演会, 応用物理学会, 山形, 国内会議
発表日 2011年09月 - Fabrication of Two-dimensional Array of Sub-10nm GaAs Nanodisk by Combination of Bio-template and Neutral Beam Etching
林 士弘; 王 宣又; 黄 啓賢; 塚本 里加子; 海津利行; 五十嵐 誠; 岡田 至崇; 寒川誠二
口頭発表（一般）, 日本語, 秋季第72回応用物理学会学術講演会, 応用物理学会, 山形, 国内会議
発表日 2011年09月 - Optical Absorption, Photo-Luminescence and Miniband Formation of a Highly Ordered and Dense 2-Dimensional Array of Si Nanodisks for Quantum Dot Solar Cells
M. Igarashi; C.H. Huang; X. Y. Wang; M. F. Budiman; Y. Tamura; T. Kiba; A. Murayama; T. Kaizu; Y. Okada; S. Samukawa
口頭発表（一般）, 英語, 37th IEEE Photovoltaic Specialists Conference, Seattle, 国際会議
発表日 2011年06月 - Damage-free Top-down Processes of Fabricating Two-dimensional Array of Sub-10nm Nanometer GaAs Nanodisks using Bio-template and Neutral Beam Etching for Intermediate Band Solar Cell Applications
X. Y. Wang; C. H. Huang; R. Tsukamoto; T. Kaizu; M. Igarashi; P. A. Mortemousque; H. Shinohara; Y. Okada; A. Murayama; K. Itoh; Y. Ohno; I. Yamashita; S. Samukawa
口頭発表（一般）, 英語, 37th IEEE Photovoltaic Specialists Conference, Seattle, 国際会議
発表日 2011年06月 - 高密度InAs量子ドットのSb照射成長中断における時間分解X線回折測定(3)
山本 和輝; 角田 直輝; 海津 利行; 高橋 正光; 藤川 誠司; 山口 浩一
口頭発表（一般）, 日本語, 秋季第71回応用物理学会学術講演会, 応用物理学会, 長崎, 国内会議
発表日 2010年09月 - シリコン(Si)ナノディスク2次元アレイによる高効率光吸収とバンドギャップエネルギー制御の実現
ブディマン モハマド; ファイルズ; 黄 啓賢; 王 宣又; 海津 利行; 五十嵐 誠; 大島 隆治; 岡田 至崇; 山下 一郎; 寒川 誠二
口頭発表（一般）, 日本語, 秋季第71回応用物理学会学術講演会, 応用物理学会, 長崎, 国内会議
発表日 2010年09月 - 高密度InAs量子ドットのSb照射成長中断における時間分解X線回折測定(2)
角田 直輝; 海津 利行; 高橋 正光; 藤川 誠司; 山口 浩一
口頭発表（一般）, 日本語, 秋季第70回応用物理学会学術講演会, 応用物理学会, 富山, 国内会議
発表日 2009年09月 - Ybドープ2次元電子系におけるYbトラップ準位の考察
海津 利行; 高増 正; 竹端 寛治; 今中 康貴
口頭発表（一般）, 日本語, 日本物理学会第64回秋季大会, 日本物理学会, 東京, 国内会議
発表日 2009年09月 - Real-time X-ray diffraction measurements during Sb-mediated SK growth and annealing of InAs quantum dots
T. Kaizu; N. Kakuda; M. Takahasi; S.Fujikawa; K. Yamaguchi
ポスター発表, 英語, 14th International Conference on Modulated Semiconductor Structures, Kobe, 国際会議
発表日 2009年07月 - Magnetotransport properties of Ytterbium doped AlxGa1-xAs/GaAs two-dimensional electron system
T. Kaizu; Y. Imanaka; K. Takehana; T. Takamasu
ポスター発表, 英語, 18th International Conference on Electronic Properties of Two-Dimensional Systems, Kobe, 国際会議
発表日 2009年07月
共同研究・競争的資金等の研究課題
- 量子ドット超格子を用いた集積化高感度電界センサの実現
和田 修; 小島 磨; 海津 利行; 原田 幸弘; 南 康夫
日本学術振興会, 科学研究費助成事業, 神戸大学, 基盤研究(C), 研究分担者, 本研究では外部の電界を量子ドット（QD）超格子構造に印加し、これを含む共振器構造を透過する光信号の変調成分をとらえることにより、電界を高感度に検出するセンサの実現を目指す。本年度は、量子効果の導入による電気光学係数自体の増大効果、および光共振器構造による光子の長寿命化による電気光学効果の増強効果、の二つの効果に焦点を合わせて研究を進めた。 QD超格子構造の電気光学係数の評価を行うための導波路素子の準備と電気光学係数評価光学系の検討を進めるとともに、光共振器構造の基本設計理論の構築に重点 をおいて研究を行い、以下のような成果を得た。
QD超格子構造を含む導波路素子については、暗電流や逆方向電圧印加特性など基本的特性を測定して光学測定への適用性を確かめた。また電気光学係数の計測光学系については、光信号偏光特性計測の精度を十分に高めるための光学系の新たな設計を行って部品選定を完了し、次年度の高精度測定系の構築の見通しを得た。
光共振器構造の設計においては、共振器のQ値増大による光子寿命の延長に起因する電気光学効果の増強と、Q値の増大に伴う透過光出力の減衰との間に生ずるトレードオフ関係を考慮しながら共振器構造の最適化を行うことが必要である。本年度は基本設計理論を構築することを目指して、多層膜構造の光学特性マトリクスを用いた計算アルゴリズムを考案し、外部電界の印加による透過光信号の位相変調信号の算定が可能であることを確認できたことにより、この計算方法が最適化探索に活用できることが分かった。, 22K04218
研究期間 2022年04月 - 2025年03月
