The effect of oxygen partial pressure on band gap modulation of Ga2O3 grown by pulsed laser deposition

Abstract

The influence of oxygen partial pressure and annealing on the properties of thin films of beta-Ga2O3 grown by pulsed laser deposition were studied. The Ga2O3 samples were deposited at a substrate temperature of 250 degrees C at an oxygen pressure of 0-50 mTorr and then annealed at a temperature of 600 degrees C. We observed the crystallinity of Ga2O3 enhanced with annealing and with increasing oxygen pressure. The full width at half maximum of annealed beta -Ga2O3 ((4) over bar 01) peaks decreased, corresponding to the grain size increasing from 6.76 nm to 11.25 nm. The conductivity of the obtained, as-grown Ga2O3 films increased with oxygen pressure from 2.1 to 7.9 mScm(-1). As a result, the conductance and the energy band gap of beta-Ga2O3 without annealing were controlled by the oxygen partial pressure. This was attributed to the oxygen vacancies, based on the composition ratio between O and Ga ions. These results clearly showed that the energy band gap and conductance of beta-Ga2O3 thin films could be controlled in such a way that could be utilized for high-performance photo-electronic devices. (C) 2019 Elsevier B.V. All rights reserved.