Correlation of pulsed gas flow on Si-doped α-Ga 2 O 3 epilayer grown by halide vapor phase epitaxy

Gallium oxide (Ga2O3) is the one of the ultra-wide-band-gap semiconductor material. The Ga2O3 semiconductor has been studied for use in highly energy efficient devices. Among its phases, the β-phase of Ga2O3 has mainly been researched until recently. However, the α-phase, which has superior properties (e.g., wider band-gap and higher symmetry) has been discussed in the electronic-materials field of late. There are problems that need to be overcome in order for the α-phase to be a suitable electronic material; one of them is the production of high-quality thin films. This article reports the fabrication of a high-quality Si-doped α-Ga2O3 epilayer on α-Al2O3 substrate by halide vapor-phase epitaxy with the controlled pulse flow of each precursor. The α-Ga2O3 epilayer grown with a controlled pulse flow of O2 has a lower full width at half maximum (FWHM; 1306 arcsec) for the 10-14 diffraction compared to the FWHM (2011 arcsec) of the as-grown sample. The pulse-flow mode of introducing Ga and O2 strongly influences the crystal quality of α-Ga2O3. In the O2-control mode, we demonstrated Si-doped α-Ga2O3 epilayers with higher electron mobility up to 51.57 cm2/Vs and wider carrier concentrations range of 1017~1019 cm-3 by improving the crystal quality.