MBE growth optimization for GaAs1−xBix and dependence of photoluminescence on growth temperature

Abstract

The effect of growth conditions on the electronic properties of GaAs1−xBix grown on GaAs by molecular beam epitaxy has been investigated by means of temperature dependent photoluminescence (PL). When the substrate temperature during growth was reduced from 400 °C to 300 °C and all other growth conditions were fixed, the Bi concentration in the deposited films increased from 1% to 5% and the PL intensity decreased by more than a factor of 1000. Two samples were grown at different temperatures (330 °C and 375 °C) with approximately the same Bi concentration (∼2%) at a stoichiometric As:Ga flux ratio. The temperature dependence of the PL shows that the sample grown at high temperature has less PL emission from sub-bandgap states and a stronger temperature dependence of the bandgap. We conclude that GaAs1−xBix samples grown at higher temperatures have a lower density of shallow and deep electronic states in the bandgap.