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

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 degrees C to 300 degrees 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 degrees C and 375 degrees C) with approximately the same Bi concentration (similar to 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.