讲座时间：2018 年 12 月24 日 下午 13：30-145：30
郭其新，日本国立佐贺大学同步辐射光应用研究中心主任，电气电子系教授，博士生导师。分别于1990，1992和1996年在日本国立丰桥技术科学大学电气电子系获得学士，硕士和博士学位。主要从事半导体材料制备与表征，同步辐射光应用研究。已在Nature Communications, Physical Review B, Journal of Applied Physics, Applied Physics Letters和Advanced Materials等期刊上发表SCI论文305余篇，H因子为42（Google Scholar）。在国际学术会议上多次做邀请报告并担任多个国际会议组织机构成员和技术委员会委员。日本学术振兴会162宽禁带光电材料委员会委员。
Current status of researches on gallium oxide
wide bandgap semiconductors
Department of Electrical and Electronic Engineering, Synchrotron Light Application Center, Saga University, Saga 840-8502, Japan
The success in obtaining high quality β-Ga2O3 bulk substrates has positioned this material as a strong candidate for next-generation devices such as ultraviolet light emitting diode and photodetector. By lowing the bandgap of Ga2O3 with indium, we have succeeded in obtaining tunable bandgap from 3.8 eV to 5.1 eV [1,2]. A wider bandgap range is of great merit as it allows the design of devices such as high sensitive wavelength-tunable photodetectors, cutoff wavelength-tunable optical filters in more broad range. Al is a candidate to enlarge the bandgap of Ga2O3 because Al2O3 has a larger bandgap (~8.8 eV) and the similar electron structures of Al and Ga makes the alloy (AlGa)2O3 possible. In this invited talk, we will report on the growth and characterization of these films.
Ga2O3 based films were deposited on (0001) sapphire substrates by pulsed laser deposition. We demonstrated that the bandgap energy of the (InGa)2O3 or (AlGa)2O3 films can be tailored by controlling the In or Al contents in the films [1-6]. We fabricated the Ga2O3:Er/Si light-emitting devices (LEDs) and observed intense green emission (548 nm) from the LEDs [7-9]. The driven voltage of the LEDs was 6.2 V which is lower than that of ZnO:Er/Si or GaN:Er/Si devices. We have also investigated structural and optical properties of Eu doped Ga2O3 films.X-ray absorption near edge structure measurements indicated that the valence of Eu ions in the Eu doped Ga2O3 films varies from mixture of bivalent and trivalent to only trivalent with increasing substrate temperature. Extended X-ray absorption fine structure analysis revealed that the Eu atoms doped in Ga2O3 matrix are incorporated on Ga sites in Ga2O3 matrix even for the films with amorphous structure grown at low substrate temperature .
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