Characterization of band offset in α-(AlxGa1-x)2O3/ α-Ga2O3 heterostructures
Gallium Oxide is a promising material for power device applications. We focused on corundum structured gallium oxide (α-Ga<sub>2</sub>O<sub>3</sub>) and α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub>/ α-Ga<sub>2</sub>O<sub>3</sub> heterostructure devices. We prepared α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> alloy and these laminate structures on c-plane sapphire substrates. The band offset of the α-Ga<sub>2</sub>O<sub>3</sub>/α-(Al<sub>x</sub>Ga<sub>1-x</sub>)<sub>2</sub>O<sub>3</sub> heterostructure was measured by X-ray photoelectron spectroscopy (XPS). The band alignment was estimated to be type I with very narrow valence-band offset energy.
Wide bandgap engineering of (AlGa)2O3 films
Bandgap tunable (AlGa)2O3 films were deposited on sapphire substrates by pulsed laser deposition (PLD). The deposited films are of high transmittance as measured by spectrophotometer. The Al content in films is almost the same as that in targets. 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, indicating PLD is a promising growth technology for growing bandgap tunable (AlGa)2O3 films.
Growth of corundum-structured In2O3 thin films on sapphire substrates with Fe2O3 buffer layers
Abstract We report the fabrication of rhombohedral corundum-structured indium oxide (α-In2O3) thin films, which can complete a semiconductor quaternary alloy system with α-Al2O3 and α-Ga2O3, on sapphire substrates with α-Fe2O3 buffer layers. X-ray diffraction showed the formation of α-In2O3, and the α-In2O3 film exhibited n-type semiconductor properties with electron concentration of 1.2×1018 cm−3 and electron mobility of 83 cm2/Vs. The α-In2O3 took grain structure with the lateral sizes of 300–600 nm, and in a grain area α-In2O3 grew epitaxially on a sapphire substrate.