Nucleation effects during MBE growth of Sn-Doped GaAs

The morphology, structure and composition of Sn films on GaAs substrates have been investigated in relation to the predeposition technique used with Sn doping of MBE-grown GaAs films. It has been shown that 3-D aggregates of Sn are formed and a similar morphology has been identified in the Sn which accumulates at the surface of all Sn-doped GaAs films. The way in which this relates to donor incorporation is considered and a simple model of incorporation kinetics proposed which is shown to be consistent with observation.