First-principles calculations of the near-edge optical properties of β-Ga2O3

We use first-principles calculations based on many-body perturbation theory to investigate the near-edge electronic and optical properties of β-Ga2O3. The fundamental band gap is indirect, but the minimum direct gap is only 29 meV higher in energy, which explains the strong near-edge absorption. Our calculations verify the anisotropy of the absorption onset and explain the range (4.4–5.0 eV) of experimentally reported band-gap values. Our results for the radiative recombination rate indicate that intrinsic light emission in the deep-ultra-violet (UV) range is possible in this indirect-gap semiconductor at high excitation. Our work demonstrates the applicability of β-Ga2O3 for deep-UV detection and emission.