Influence of silicon doping on vacancies and optical properties of Al_xGa_(1-x)N thin films

摘要

The authors have used positron annihilation spectroscopy and photoluminescence measurements to study the influence of silicon doping on vacancy formation in AlGaN:Si structures. The results show a correlation between the Doppler broadening measurements and the intensity from 510 nm photoluminescence transition. The reduction in the W parameter when the [Si]/[Al+Ga] fraction in the gas phase is above 3 X 10~(-4) indicates that the positrons annihilate in an environment where less Ga 3d electrons are present, i.e., they are trapped in group-Ill vacancies. The observation of vacancies at these silicon concentrations coincides with the onset of the photoluminescence transition at 510 nm.