講座時間：2018 年 12 月24 日 下午 13：30-145：30
郭其新，日本國立佐賀大學同步輻射光應用研究中心主任彩票123安卓下载，電氣電子系教授，博士生導師。分別于1990，1992和1996年在日本國立豐橋技術科學大學電氣電子系獲得學士，碩士和博士學位。主要從事半導體材料制備與表征，同步輻射光應用研究。已在Nature Communications, Physical Review B, Journal of Applied Physics, Applied Physics Letters和Advanced Materials等期刊上發表SCI論文305余篇，H因子為42（Google Scholar）。在國際學術會議上多次做邀請報告并擔任多個國際會議組織機構成員和技術委員會委員。日本學術振興會162寬禁帶光電材料委員會委員。
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 .
 F. Zhang, K. Saito, T. Tanaka, M. Nishio, Q. Guo, Solid State Commun. 186, 28 (2014).
 F. Zhang, K. Saito, T. Tanaka, M. Nishio, Q. Guo, J. Alloy. Compd. 614, 173 (2014).
 F. Zhang, K. Saito, T. Tanaka, M. Nishio, M. Arita, Q. Guo, Appl. Phys. Lett. 105, 162107 (2014).
 G. Li, F. Zhang, Y. Cui, H. Oji, J. Son, Q. Guo, Appl. Phys. Lett. 107, 022109 (2015).
 F. Zhang, M. Arita, X. Wang, Z. Chen, K. Saito, T. Tanaka, M. Nishio, T. Motooka, Q. Guo, Appl. Phys. Lett. 109, 102105 (2016).
 X. Wang, Z. Chen, F. Zhang, K. Saito, T. Tanaka, M. Nishio, Q. Guo, AIP Advances 6, 015111 (2016).
 Z. Chen, X. Wang, F. Zhang, S. Noda, K. Saito, T. Tanaka, M. Nishio, M. Arita, Q. Guo, Appl. Phys. Lett. 109, 022107 (2016).
 Z. Chen, K. Nishihagi, X. Wang, K. Saito, T. Tanaka, M. Nishio, M. Arita, Q. Guo, Appl. Phys. Lett. 109, 102106 (2016).
 Z. Chen, K. Saito, T. Tanaka, Q. Guo, CrystEngComm 19, 4448 (2017).
 K. Nishihagi, Z. Chen, K. Saito, T. Tanaka, Q. Guo, Mat. Res. Bull. 94, 170 (2017).