The effect of O2 high-temperature annealing on the quality of Al2O3/Ga2O3 interface

In this study, a passivation technique with reduced process complexity for β-Ga2O3 surface passivation is reported. Through the process of rapid annealing at a high temperature of 1300 K in an oxygen atmosphere, oxygen atoms are introduced into the surface of Ga2O3 crystal to fill the oxygen vacancy in Ga2O3 crystal, reduce the defects on the surface of Ga2O3, and then passivate the β-Ga2O3 surface. A significant increase in the oxygen atom content on the surface of the annealed Ga2O3 crystals was confirmed by electron probe x-ray microanalysis and x-ray photoelectron spectroscopy analyses. The prepared Al2O3/β-Ga2O3 metal oxide semiconductor capacitor devices have a low interfacial trap density with Dit = 1.6 × 1011 cm−2 eV−1 and low frequency dispersion characteristics as well as a small low-frequency-dependent flatband voltage shift ΔVFB(f). Simultaneous enhancement of device breakdown voltage and optimization of surface defects by a simple high-temperature annealing technique provide an alternative approach for improving performance in β-Ga2O3 power devices.