Correlation of Pulsed Gas Flow on Si-doped α-Ga₂O₃ Epilayer Grown by Halide Vapor Phase Epitaxy

Abstract

Gallium oxide (Ga 2 O 3 ) is the one of the ultra-wide-band-gap semiconductor material. The Ga 2 O 3 semiconductor has been studied for use in highly energy efficient devices. Among its phases, the β -phase of Ga 2 O 3 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 -Ga 2 O 3 epilayer on α -Al 2 O 3 substrate by halide vapor-phase epitaxy with the controlled pulse flow of each precursor. The α -Ga 2 O 3 epilayer grown with a controlled pulse flow of O 2 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 O 2 strongly influences the crystal quality of α -Ga 2 O 3 . In the O 2 -control mode, we demonstrated Si-doped α -Ga 2 O 3 epilayers with higher electron mobility up to 51.57 cm 2 V −1 s −1 and wider carrier concentrations range of 10 17 ∼ 10 19 cm −3 by improving the crystal quality.