Qixin GuoProfessor of Department of Electrical and Electronic Engineering
Director of Synchrotron Light Application Center, Saga University, Japan
Speech Title: Epitaxial growth and characteristics of gallium oxide based ultrawide bandgap semiconductors
Abstract: The Si based technologies were spawned by the demonstration of the first transistor. Until the early 1990s, semiconductor technologies were limited to Si and the conventional III-V compounds such as GaAs and GaP which have relatively narrow bandgap of less than 2.3 eV. The ultrawide bandgap semiconductors in-cluding Ga2O3, Diamond, and AlN which have bandgaps significantly larger than the 3.4 eV of GaN had proven extremely challenging to develop, despite their obvious potential advantages for optoelectronics and higher breakdown voltages for power electronics. The success in obtaining high quality β-Ga2O3 bulk sub-strates has positioned this material as a strong candidate for next-generation devices such as ultraviolet light emitting diode and photodetector. 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 talk, we will report on the growth and characterization of these films. Ga2O3 based oxide films were deposited on (0001) sapphire substrates by oxygen plasma assisted pulsed laser deposition. We have demonstrated that the bandgap energy of the (AlGa)2O3 films can be tailored by controlling the Al contents in the films at the growth temperature as low as 200℃. Recent progress on the growth of these ultrawide oxide semiconduc-tors will also been reported.
Biography: Prof. Dr. Guo received B. E., M.E., and Dr. E degrees in electronic engineering from Toyohashi University of Technology in 1990, 1992, and 1996, respectively. He is currently a Professor of Department of Electrical and Electronic Engineering, Saga University as well as Director of Saga University Synchrotron Light Application Center. His research interests include epitaxial growth and characterization of semiconductor materials. Prof. Guo has published more than 300 papers in scientific journals including Nature Communications, Advanced Materials, Physical Review B, and Applied Physics Letters with more than 6000 citations (h-index: 41)