Properties and electronic structure of heavily oxygen-doped GaN crystals

We investigated the properties of heavily oxygen-doped single GaN crystals and proposed their electronic structure based on first-principle calculations. The crystals were grown by carbothermal reduction and nitridation of Ga2O3 at 1180 °C for 2–8 h. The crystals were found to have high-crystallinity and high-concentration oxygen (4–9 × 1020 atoms/cm3). Cathodoluminescence measurements of the 8-h-grown crystals showed a shift of band-edge-related luminescence peak toward higher energy (ca. 120 meV). Density of state of oxygen-doped GaN supercell was calculated using the first-principle to support this upward shift of luminescence energy.