Applied Crystallography

Biography

Biography: Qixin Guo

Abstract

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. These achievements should be followed by bandgap engineering because it allows great flexibility in designing and optimizing the devices. 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 work, we report on the crystal growth and characterization of (AlGa)₂O₃ films.We fabricated (AlGa)₂O₃ films on (0001) sapphire substrates by pulsed laser deposition using a KrF excimer laser source with wavelength 248 nm. The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra using X-ray photoelectron spectroscopy is proved to be valid for determining the bandgap of (AlGa)₂O₃ films as it is in good agreement with the bandgap values from transmittance spectra. The measured bandgap of (AlGa)₂O₃ films increases continuously with the Al content covering the whole Al content range from about 5 to 7 eV.  Recent progress on these materials will be presented.