Electrical and Structural Properties of Two-Inch Diameter (0001) α-Ga2O3 Films Doped with Sn and Grown by Halide Epitaxy

Abstract

Two-inch diameter α-Ga2O3 films with thickness ∼4 μm were grown on basal plane sapphire by Halide Vapor Phase Epitaxy (HVPE) and doped with Sn in the top ∼1 μm from the surface. These films were characterized with High-Resolution X-ray Diffraction (HRXRD), Scanning Electron Microscope (SEM) imaging in the Secondary Electron (SE) and Micro-cathodoluminescence (MCL) modes, contactless sheet resistivity mapping, capacitance-voltage, current-voltage, admittance spectra, and Deep Level Transient Spectroscopy (DLTS) measurements. The edge and screw dislocations densities estimated from HRXRD data were respectively 7.4 × 109 cm−2 and 1.5 × 107 cm−2, while the films had a smooth surface with a low density (∼103 cm−2) of circular openings with diameters between 10 and 100 μm. The sheet resistivity of the films varied over the entire 2-inch diameter from 200 to 500 Ω square−1. The net donor concentration was ∼1018 cm−3 near the surface and increased to ∼4 × 1018 cm−3 deeper inside the sample. The deep traps observed in admittance and DLTS spectra had levels at Ec−0.25 eV and Ec−0.35 eV, with concentration ∼1015 cm−3 and Ec−1 eV with concentration ∼1016 cm−3.