Abstract: Ultrawide bandgap semiconductor (AlGa)₂O₃, which has a tunable bandgap between 4.9 (Ga₂O₃) and 8.7 eV (Al₂O₃), has recently emerged as a promising material for optoelectronic applications. The (AlGa)₂O₃ based solid state devices are almost based on material structures created by thin film deposition. Thus, the deposition technology can be regarded as one of the keys to the fabrication of (AlGa)₂O₃ based devices. Various growth techniques have been explored to deposit (AlGa)₂O₃ films, including sputtering, molecular beam epitaxy, mist chemical vapor deposition, metal organic chemical vapor deposition, and pulsed laser deposition (PLD). Among these deposition methods, PLD is a good candidate technology for low temperature growth because the ablated species generated in the PLD process have relatively high kinetic energies. In another aspect, the oxygen plasma has been found to be an effective assistant species for decreasing the growth temperature of thin films. Thus, the combination of PLD and oxygen plasma assistance should be a very effective method for low temperature film growth. In this talk, we report on the low temperature growth of (AlGa)₂O₃ films by oxygen plasma assisted PLD. The prepared films show a good (−201) orientation perpendicular to (0001) sapphire substrates even at a deposition temperature as low as 200 °C. The influences of the substrate temperature on the structural and optical properties of the films have been systematically investigated. Recent progress on the growth of these ultrawide oxide semiconductors will also been presented.

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 6800 citations (h-index: 43).