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108 results on '"Pan, Wugen"'

4. Influence of growth temperature on minority-carrier lifetime of Si layer grown by liquid phase epitaxy using Ga solvent

Author

Satoh, Yusuke, Usami, Noritaka, Pan, Wugen, Fujiwara, Kozo, Nakajima, Kazuo, and Ujihara, Toru

Subjects
Mass spectrometry -- Usage, Silicon compounds -- Electric properties, Gallium compounds -- Electric properties, Physics
Abstract

The influence of growth temperature on the minority-carrier lifetime of epitaxial Si layers is systematically investigated. Results suggest that low growth temperature should be employed in growing a Si film with minority-carrier lifetime.

Published
2005

8. Improvement in the conversion efficiency of single-junction SiGe solar cells by intentional introduction of the compositional distribution.

Author

Tayanagi, Misumi, Usami, Noritaka, Pan, Wugen, Ohdaira, Keisuke, Fujiwara, Kozo, Nose, Yoshitaro, and Nakajima, Kazuo

Subjects
PHOTOVOLTAIC cells, SOLAR cells, QUANTUM wells, SEMICONDUCTOR doping, DIFFUSION
Abstract

We attempted to clarify the impact of the compositional distribution on recently reported improvement in the conversion efficiency of solar cells based on bulk multicrystalline SiGe. For this purpose, Si1-xGex/Si1-yGey multiple quantum well structures on heavily doped Si-on-insulator were employed as model crystals. The combination of x and y, the width of each layer, and the number of repetitions were systematically changed to study the influence of the introduction of Ge on photocarrier generation and carrier transport while keeping the average Ge composition as 0.03. Spatial modulation of the band structure leads to formation of quantum wells for holes and gives negative impact especially in the photocarrier collection from the n-type region. When the depth of wells was designed to be constant, short-circuit carrier density was found to show a maximum at appropriate compositional distribution due to the competition between the increase in the photocarrier generation and the decrease in the minority carrier diffusion length. Within a limited compositional range, the overall performance of the solar cell was revealed to be improved by the introduction of the compositional distribution compared with that based on uniform Si0.97Ge0.03. Therefore, intentional introduction of the compositional distribution is concluded to be useful for improvement in the solar cell performance if appropriate dispersion is chosen. [ABSTRACT FROM AUTHOR]

Published
2007
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10. Ge composition dependence of properties of solar cells based on multicrystalline SiGe with microscopic compositional distribution

Author

Pan, Wugen, Fujiwara, Kozo, Usami, Noritaka, Ujihara, Toru, and Shimokawa, Ryuichi

Subjects
Silicon -- Research, Silicon -- Properties, Germanium -- Research, Germanium -- Properties, Solar batteries -- Analysis, Solar cells -- Analysis, Physics
Abstract

The device performance of solar cells based on multicrystalline SiGe(mc-SiGe) bulk crystal with microscopic compositional distribution grown by the casting method is presented. The results demonstrate that mc-SiGe is a promising candidate to replace mc-Si as it could achieve higher conversion efficiency without drastic increase of the production cost.

Published
2004

11. Vertical antiresonant reflecting optical waveguide coupler for three-dimensional optical interconnects: optimum design for large tolerance, high coupling efficiency, and short coupling length

Author

Sekimoto, Takashi, Ikuta, Shigenori, Pan, Wugen, Chu, Sai Tak, and Kokubun, Yasuo

Subjects
Optics -- Research, Images, Optical -- Measurement, Waveguide junctions -- Research, Astronomy, Physics
Abstract

A compact antiresonant-reflecting-optical-waveguide- (ARROW-) type vertical coupler for three-dimensional optical interconnects was demonstrated. The coupler consists of stacked ARROW's channeled by the stripe lateral confinement structure, and each waveguide is completely separated by a thin metal film in the separation region. In the coupling region the intermediate cladding of a previous coupler was made of the same material as that of the first cladding or the core. However, we had to overcome the problem that both the high coupling efficiency and the large fabrication tolerance cannot be achieved simultaneously. Thus we incorporated an intermediate cladding made of a material different from that of the core and the first cladding. The refractive index and the thickness of the intermediate cladding were optimally designed to achieve large fabrication tolerance and a short coupling length with a high coupling efficiency. The coupling length was reduced from 4.1 to 0.8 mm, and a high coupling efficiency of 96% was experimentally demonstrated. [C] 2000 Optical Society of America OCIS codes: 230.3120, 230.7380, 250.5300.

Published
2000

40. Metalorganic Vapor Phase Eitaxy Growth Features of AlGaAs in Tetrahedral-Shaped Recesses on GaAs (111)B Substrates

Author

Tomoko Tsujikawa, Tomoko Tsujikawa, primary, Wugen Pan, Wugen Pan, additional, Keishi Momma, Keishi Momma, additional, Masahiro Kudo, Masahiro Kudo, additional, Kunio Tanaka, Kunio Tanaka, additional, Hiroyuki Yaguchi, Hiroyuki Yaguchi, additional, Kentaro Onabe, Kentaro Onabe, additional, Yasuhiro Shiraki, Yasuhiro Shiraki, additional, and Ryoichi Ito, Ryoichi Ito, additional

Published
1997
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50. Effects of formation of mini-bands in two-dimensional array of silicon nanodisks with SiC interlayer for quantum dot solar cells.

Author

Igarashi, Makoto, Budiman, Mohd Fairuz, Pan, Wugen, Hu, Weiguo, Tamura, Yosuke, Syazwan, Mohd Erman, Usami, Noritaka, and Samukawa, Seiji

Subjects
SOLAR cells, QUANTUM dot devices, SILICON, NANOTECHNOLOGY, TWO-dimensional models, ELECTRIC properties of materials, OPTICAL properties, ETCHING
Abstract

A sub-10 nm, high-density, periodic silicon nanodisk (Si-ND) array with a SiC interlayer has been fabricated using a new top-down process that involves a 2D array of a bio-template etching mask and damage-free neutral beam etching. Optical and electrical measurements were carried out to clarify the formation of mini-bands due to wavefunction coupling. We found that the SiC interlayer could enhance the optical absorption coefficient in the layer of Si-NDs due to the stronger coupling of wavefunctions. Theoretical simulation also indicated that wavefunction coupling was effectively enhanced in Si-NDs with a SiC interlayer, which precisely matched the experimental results. Furthermore, the I-V properties of a 2D array of Si-NDs with a SiC interlayer were studied through conductive AFM measurements, which indicated conductivity in the structure was enhanced by strong lateral electronic coupling between neighboring Si-NDs. We confirmed carrier generation and less current degradation in the structure due to high photon absorption and conductivity by inserting the Si-NDs into p-i-n solar cells. [ABSTRACT FROM AUTHOR]

Published
2013
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