【International Papers】Further Characterization of the Polycrystalline p-Type β-Ga₂O₃ Films Grown through the Thermal Oxidation of GaN at 1000 to 1100 °C in a N₂O Atmosphere

      Researchers from the Jimei University have published a dissertation titled " Further characterization of the polycrystalline p-type β-Ga₂O₃ films grown through thermal oxidation of GaN at 1000 to 1100 °C in N₂O atmosphere " in preprints.org.

Abstract

      The development of good conductivity p-type β-Ga₂O₃ is critical to realize its devices and applications. The nitrogen-doped p-type β-Ga₂O₃ films with enhanced conductivity characteristics were prepared through the thermal oxidation of GaN in the N₂O atmosphere. 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.

Figure 1. (a) PL emission spectra of the thermally oxidized samples at 1000, 1050, and 1100 ℃ within the wavelength range of 242-300 nm at room temperature. The emission was excited using grating spectrophotometry. (b) PL emission spectra of the thermally oxidized samples at 1000, 1050, and 1100°C within the wavelength range of 325–700 nm at room temperature. The inserted image is the PL spectrum of the undoped GaN substrate. The emission was excited using a 325-nm He-Cd laser.

Paper Link：https://doi.org/10.3390/coatings13091509