Investigation of origin of polycrystalline defect in homoepitaxial (01¯1¯) <b> <i>β</i> </b> -Ga2O3 layers grown by halide vapor phase epitaxy using synchrotron x-ray topography and energy-dispersive x-ray spectroscopy

Abstract

We demonstrate that (01¯1¯) [or (011)] β-Ga2O3 is a promising orientation for halide vapor phase epitaxy (HVPE) homoepitaxial growth for realization of thick epitaxial layers with low donor concentration. Mercury capacitance–voltage measurements indicate a net donor concentration in the range of 4 × 1014–2 × 1015 cm−3, which is suitable for high-power device applications. However, the presence of polycrystalline defects was confirmed over the entire as-grown HVPE surface, with a density of approximately 1.3 × 102 cm−2. X-ray topography measurements showed that the formation of these polycrystalline defects is not triggered by dislocations in the substrate. Optical microscopy observation confirmed the presence of cores within the polycrystalline defects near the epilayer/substrate interface. Additionally, cross-sectional energy-dispersive x-ray spectroscopy identified SiOx contaminations originating from the quartz of the chamber sidewall are the cause of the formation of these polycrystalline defects.