Research

Research Subjects

Partial Dislocation Motion Associated with Expantion or Contraction of Stacking Faults in 4H-SiC

Elementary Process of PD motion	We observe the shrink motion of SF and investigate the elementary process of PD motion which forms a border of SF.
PD Motion under Electric Excitation	We investigae the enhancement effects of PD motion under electric excitation using SEM.

Evaluation and Control of Impurity Level on Grain Boundary in mc-Si for Solar Cells

We found that annealing with reverse bias eliminate impurity levels in mc-Si for Solar Cells. We study the effects in detail and try to control the harmful level for photovoltaics.

Defect Evaluation in beta-Ga2O3 Single Crystals

We are investigating the effects of hydrogen- and oxygen-plasma treatment on the electrical properties of beta Ga2O3.

Doping Effects on Dislocatoin Motion in SiGe films on Si Substrate

We had studied dislocation motion in SiGe epitaxial films, which is expected as a material for high-speed devices.

Enhancement Effects on Dislocation Motion by Sb-doping	We found the enhancing effects of dislocation motion in a SiGe film by Sb doping. This is the Fermi-level effect which was known in other semiconductors.

Recent Publications

• Yoshifumi Yamashita, Ryu Nakata, Takeshi Nishikawa, Masaki Hada, and Yasuhiko Hayashi, "Expansion of Shockley stacking fault observed by scanning electron microscope and partial dislocation motion in 4H-SiC", J. Appl. Phys., 123(16),161580 (2018).
• Kiichiro Tagawa, Yuta Miyabe, Keishi Yasuda, Yoshifumi Yamashita, Takeshi Nishikawa, Masaki Hada, Yasuhiko Hayashi, "Reverse-bias effects of metal-related levels in mc-Si for solar cells studied by isothermal DLTS", Proc. The Forum on the Science and Technology of Silicon Materials 2018 pp.300-306 (2018)
• Nobuchika Nagai, Toshiki Tanaka, Yoshifumi Yamashita, Masaki Hada, Takeshi Nishikawa, Yasuhiko Hayashi, "Effects of remote hydrogen-plasma treatment on electrical properties of b-Ga₂O₃", Proc. The Forum on the Science and Technology of Silicon Materials 2018 pp.387-391 (2018)
• Yoshifumi Yamashita, Kan Tanemoto, Akihiro Tanaka, and Tatsuya Fushimi, "Effects of Sb-doping on Strain Relaxation of SiGe Film on Si Substrate", AIP Conference Proceedings,1583, 119 (2014).