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Affiliation |
Engineering educational research section Applied Physics and Engineering Program |
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Associate Professor |
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SUZUKI Hidetoshi
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Papers 【 display / non-display 】
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Ogura A., Nogawa S., Kawano M., Minematsu R., Suzuki H.
Applied Physics Express 14 011001 2020.12
Language：English Publishing type：Research paper (scientific journal)
By using synchrotron X-ray diffraction, we investigated the in-plane distribution of preferential glide planes in a metamorphic InGaAs solar cell with a relatively low open-circuit voltage (Voc) compared to other cells fabricated on the same wafer. The reciprocal-space maps revealed that the low-Voc cell contains several domains with different preferential glide planes of β dislocations. Since fluctuations of the average β-glide plane have not been observed for high-Voc cells, the observed inhomogeneous distribution should be related to the Voc degradation. Understanding preferential glide-plane changes within a cell can help to improve the uniformity of cell properties over the whole wafer.
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Ogura A., Yi W., Chen J., Suzuki H., Imaizumi M.
Journal of Electronic Materials 49 ( 9 ) 5219 - 5225 2020.9
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Electronic Materials
© 2020, The Minerals, Metals & Materials Society. Epitaxial growth of lattice-mismatched materials is useful for solar cells, but lattice dislocations must be controlled for best device performance. It has been shown that metamorphic growth enables fabrication of InGaAs p–n junctions with good performances on GaAs substrates due to the insertion of buffer layers. Here, we investigate misfit and threading dislocations inside the step-graded InGaP buffer layers of a single-junction InGaAs solar cell by cathodoluminescence microscopy. Prior to measurement, the device edges were polished at various angles (less than 10° with respect to the substrate surface). By using this technique, cross sections of very thin layers can be directly imaged with a resolution that allows us to observe misfit and threading dislocations. In the present device, the densities of the two types of dark lines depend on the position in the buffer structure. In particular, near the InGaAs base layer, the density of the dark lines extending in the [110] direction is higher than that of the dark lines extending in the [1-10] direction. We believe that this difference in the dark line density is related to the surface morphology.
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Suzuki H., Ishikawa F., Sasaki T., Takahasi M.
Applied Physics Express 13 ( 5 ) 2020.5
Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Physics Express
© 2020 The Japan Society of Applied Physics. We carry out real-time in situ synchrotron X-ray diffraction on the growth of GaN and AlN on SiC(0001) substrate by molecular beam epitaxy. At the initial growth stage of GaN/SiC or AlN/SiC heterostructure, the epitaxial overlayer develops affected by defects with the strain interaction between SiC, eventually showing characteristic lattice deformations. GaN was almost relaxed at the initial stage, showing the transition of the growth mode from 3D to 2D at around 4 nm. In contrast, AlN coherently grow on SiC(0001) at the initial stage for 13 nm concomitantly showing lattice deformation with the beneath SiC, subsequently showing gradual lattice relaxation.
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Kawano M., Minematsu R., Haraguchi T., Fukuyama A., Suzuki H.
Japanese Journal of Applied Physics 59 ( SG ) SGGF10 2020.4
Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics
© 2020 The Japan Society of Applied Physics. GaAsN films with different N distributions have been grown using the atomic layer epitaxy method to evaluate the effects of N distribution on the electrical properties of GaAsN. Three films, which had the same N composition with different N distribution were fabricated by alternate stack of GaAsN 1 monolayer (ML) and GaAs (0, 3, 5) ML. According to the X-ray diffraction measurement, periodicity and small N interdiffusion between GaAs and GaAsN layers in grown GaAsN films were confirmed. Thus, N distribution in the films were successfully modified in the order of a few unit lattice. Contribution of each scattering mechanisms on carrier mobility and densities of scattering centers in grown GaAsN films were evaluated. Compared with the film with 0 ML of GaAs, the density of N induced scattering center decreased with insertion of GaAs 3 ML between GaAsN 1 ML. It again increased the film with insertion of GaAs 5 ML. These results suggest that controlling N distribution intentionally not only degraded but also improved the electrical properties of GaAsN films.
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Ogura A., Suzuki H., Imaizumi M.
Journal of Crystal Growth 533 2020.3
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Crystal Growth
© 2019 Elsevier B.V. Metamorphic growth of light absorber layers of solar cells introduces misfit dislocations due to strain relaxation, and their influences on the solar cell performance need to be characterized. In this work, we correlate the asymmetry of relaxation probabilities via different glide planes (which results in a tilt of the epilayer) with the open-circuit voltages (Voc) of several metamorphic InGaAs single junction solar cells. The devices contain graded InGaP buffer layers and are grown on a GaAs 001 wafer with a small miscut towards the 100 direction. We observe an inhomogeneous distribution of the solar cells’ Voc within the wafer and are able to correlate the Voc fluctuation to a difference in the asymmetry of the glide plane distributions of α and β dislocations. In the case of solar cells exhibiting a high Voc, the glide planes of both α and β dislocations are controlled by the surface orientation. In the case of low-Voc samples, the glide planes of the β dislocations are controlled by the ordering of InGaP, while those of the α dislocations are still controlled by the surface orientation.
Books 【 display / non-display 】
MISC 【 display / non-display 】
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Sasaki T., Suzuki H., Sai A., Takahasi M., Fujikawa S., Kamiya I., Ohshita Y., Yamaguchi M.
Journal of Crystal Growth 387 2014.2
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：Journal of Crystal Growth
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Ohshita Y., Suzuki H., Kojima N., Tanaka T., Honda T., Inagaki M., Yamaguchi M.
Journal of Crystal Growth 374 2013.7
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：Journal of Crystal Growth
© 2013 Elsevier B.V. The affiliation of the second author should be corrected. The correct affiliation is as follows. Interdisciplinary Research Organization, University of Miyazaki, 1-1 Gakuen Kibana-dai Nishi, Miyazaki 889-2192, Japan.
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Sasaki T., Suzuki H., Takahasi M., Ohshita Y., Kamiya I., Yamaguchi M.
Journal of Applied Physics 113 ( 19 ) 2013.5
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：Journal of Applied Physics
DOI： 10.1063/1.4804236
Presentations 【 display / non-display 】
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GaAs基板上InGaAsバッファ層を用いたType-Ⅱ量子井戸の成長と評価
高島 陸人、本部 好記、臼井 一旗、國武 幸一郎、鈴木 秀俊、荒井 昌和
第71回応用物理学会春季学術講演会 2024.3.22
Event date： 2024.3.22 - 2024.3.25
Language：Japanese Presentation type：Oral presentation (general)
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Photoluminescence Intensity Dependence of InGaAs MQW on Relaxation Layer Composition on GaAs Substrate International conference
Usui K., Hombu K., Suzuki H., Arai M.
28th Microoptics Conference, MOC 2023
Event date： 2023.9.24 - 2023.9.27
Language：English Presentation type：Poster presentation
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Relationships between Distribution of Dislocation Glide Planes and Carrier Recombination Properties in InGaAs Solar Cells Using Microwave Photoconductivity Decay Mapping and Photoluminescence Spectroscopy International conference
Harada S., Suzuki H., Ogura A., Imaizumi M., Ikari T., Fukuyama A.
28th Microoptics Conference, MOC 2023
Event date： 2023.9.24 - 2023.9.27
Language：English Presentation type：Poster presentation
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微傾斜GaAs基板上にALE法を用いて成長方向と面内方向にN分布を制御したGaAsN薄膜の作製
平川 翔太、河野 将大、高木 俊作、鈴木 秀俊
第84回応用物理学会秋季学術講演会 2023.9.20
Event date： 2023.9.19 - 2023.9.23
Language：Japanese Presentation type：Oral presentation (general)
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Mapping of Dislocation-Related Carrier Nonradiative Recombination in InGaAs Solar Cells Using a Laser Heterodyne Photothermal Displacement Method International conference
Shogo Harada, Tomoki Harada, Hidetoshi Suzuki, Akio Ogura, Mitsuru Imaizumi, Tetsuo Ikari, Atsuhiko Fukuyama
2023 International Conference on Solid State Devices and Materials 2023.9.7
Event date： 2023.9.5 - 2023.9.8
Language：English Presentation type：Poster presentation
Awards 【 display / non-display 】
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応用物理学会講演奨励賞
2020.3 日本応用物理学会 成長温度の異なるGaAsSb/GaAs(001)の格子緩和異方性評価
久保 幸士朗,野川 翔太，河野 将大，佐々木 拓生，高橋 正光，鈴木 秀俊
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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PVSEC poster aword
2016.10 PVSEC organizing committee Nucleation layer grown by atomic layer deposition for selective-area growth of GaAs on patterned Si substrates by using chemical beam epitaxy
Yu-Cian Wang, Hidetoshi Suzuki, Yuki Yokoyama, Tetsuo Ikari, Atsuhiko Fukuyama, Nobuaki Kojima, Yoshio Ohshita,Masafumi Yamaguchi
Award type：Award from international society, conference, symposium, etc. Country：Singapore
Grant-in-Aid for Scientific Research 【 display / non-display 】
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格子不整合エピタキシャル膜における転位異方性が異なる「結晶粒」発生起源の解明
Grant number：23K04603 2023.04 - 2026.03
独立行政法人日本学術振興会 科学研究費基金 基盤研究（C）
Authorship：Principal investigator
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原子層エピタキシー法を用いた希薄窒化物半導体中の窒素分布三次元制御
Grant number：20K05346 2020.04 - 2023.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
希薄窒化物半導体は、SiやGeに格子整合可能でバンドギャップエネルギーを広範囲に制御可能であり、格子整合させた多接合太陽電池や光電子集積回路に期待されている。しかし、窒素(N)原子導入による電気特性の劣化が問題となっている。その原因として膜中のN分布の不均一性が考えられているが、直接N分布を観察することが困難なため、本質的な理解には至っていない。本研究では、希薄窒化物半導体であるGaAsN膜中において、(i)N原子の空間分布を三次元で制御したGaAsN薄膜の作製、(ii)実際のN分布の評価、(iii)N原子の空間分布がN局在準位(EN)および電気特性に与える影響の解明、の３点が目的である。これまでにN分布制御は試みられているが、成長方向への制御のみであった。本研究により、GaAsN膜中のN原子の三次元的な空間分布とENおよび電気特性との関係が明らかになれば、GaAsNも含めた希薄窒化物半導体材料全ての高品質化に指針を与える。
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原子層エピタキシー法を用いた希薄化物半導体の窒素空間分布制御
2016.04 - 2019.03
科学研究費補助金 若手研究(B)
Authorship：Principal investigator
本研究では、希薄窒化物半導体であるGaAsN膜中の窒素(N)原子の空間分布と、エネルギーバンド中にN原子が作るN局在準位(EN)との関係を明らかにし、ENの変化が電気特性に与える影響を知る事が目的である。申請者等はこれまでにGaAsN膜のENの評価を行い、N組成で一意に決まらずN原子の空間分布および電気的特性にも大きく関わっている可能性を見いだしているが、これらの具体的な相関は明らかになっていない。本研究により、GaAsN膜中のN原子の空間分布と電気特性との関係が明らかになれば、本材料も含めた希薄窒化物半導体材料全ての電気的特性を飛躍的に向上させるブレイクスルーとなる事が期待される。
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希土類の価数変化を利用した新しいタイプの 高分解能X線検出材料の開発
2016.04 - 2019.03
科学研究費補助金 基盤研究(C)
Authorship：Coinvestigator(s)
Available Technology 【 display / non-display 】
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多接合太陽電池用新材料の開発
III-V 族化合物半導体の結晶成長
放射光を用いた半導体結晶の構造評価Home Page： ・宮崎大学工学部応用物理工学プログラムHP
Related fields where technical consultation is available：・各種物質の同定、結晶構造、欠陥評価、(X 線回折、電子回折)。
・半導体材料の構造・電気特性評価
・放射光施設の高輝度 X 線を利用した構造評価、その場測定Message：・物質の構造評価、特に X 線や電子線を用いた手法を得意としています。
・これらのことで迷うことがありましたら、是非ご相談ください。