Structural properties 3: Vacancy defects studied with positron annihilation spectroscopy

Abstract

Positron annihilation spectroscopy has been applied to study vacancy defects in Ga2O3. Both positron lifetime and Doppler broadening experiments have been performed, both in bulk single crystals and in thin films. The results show that Ga vacancy defects are efficiently formed in thin film growth and account for the electrical compensation in semi-insulating and highly resistive Ga2O3. Their concentrations are very low in n-type material. In (InxGa1−x)2O3 alloys, the nature and behavior of the cation vacancy defects change from Ga2O3-like to In2O3-like along with the crystalline phase. Further work is important to elucidate the details of the vacancy formation mechanisms and the origins of the exceptionally strongly anisotropic positron annihilation signals.