Further Characterization of the Polycrystalline P-Type Β-Ga2o3 Films Grown Through Thermal Oxidation of Gan at 1000 to 1100 °C in N2o Atmosphere

Abstract

We reported that the nitrogen-doped p-type β-Ga2O3 films with the Hall hole concentrations above 2.55 × 1016 cm−3 were successfully grown on the top of the n-type GaN in N2O ambient at 1000 to 1100 °C [J. MATER. RES. TECHNOL. 21, 3113-3128 (2022)]. Based on the same experiments, further measurements were performed on the oxidized films at 1000, 1050, and 1100 °C to have insight into the underlying mechanism of the thermally activated transformation process. The room temperature photoluminescence (PL) spectra demonstrated a moderate ultraviolet emission peak at 246 nm, confirming the generation of gallium oxide with a band gap of ~5.0 eV. The normalized X-ray diffraction (XRD), the high-resolution transmission electron microscopy (HRTEM), and the selected area electron diffraction (SAED) patterns were used to confirm the characteristic of polycrystalline and anisotropic growth. Then, the effects of the oxidation temperature on the amount of incorporated nitrogen were analyzed using secondary ion mass spectrometry (SIMS). Moreover, the ionization energy of the acceptor of films oxidized at 1000, 1050, and 1100 °C was calculated and analyzed using the temperature-dependent Hall test results. The results showed that nitrogen doping was the main contributor to p-type electrical properties. The activation energy of the polycrystalline β-Ga2O3 prepared through thermal oxidation of GaN in the N2O atmosphere was estimated to be 147.175 kJ·mol-1 using the Arrhenius plot, which was considerably lower than that of both dry and wet oxidations of GaN in O2 ambient, thus confirming the efficiency of thermal oxidation of GaN in N2O.

Keywords: gallium oxide, thermal oxidation, p-type conductivity, polycrystalline crystal