Oxygen diffusion in β-Ga2O3 single crystals at high temperatures

Monoclinic gallium oxide (β-Ga2O3) is an ultra-wide bandgap semiconductor with importance in various technological areas. We investigated oxygen tracer self-diffusion in (100) oriented β-Ga2O3 single crystals at high temperatures between 1200 °C and 1600 °C. Isotope enriched 18O2 gas was used as a tracer source. The isotope exchanged samples were analyzed by secondary ion mass spectrometry in depth profile mode. The diffusivities can be described by the Arrhenius law with an activation enthalpy of (3.2 ± 0.4) eV. Possible diffusion mechanisms are discussed using defect equilibria and density functional theory calculations as found in the literature. As a result, oxygen interstitials are more likely than vacancies as defects governing diffusion.