A MONTE-CARLO STUDY OF GALLIUM DESORPTION-KINETICS DURING MBE OF (100)-GAAS ALGAAS HETEROSTRUCTURES/

In situ desorption mass spectrometry studies (DMS) of AlGaAs/GaAs mole cular beam epitaxy (MBE) at high substrate temperatures reveals a rich transient behavior in the Ga desorption signal during the formation o f the AlGaAs-on-GaAs interface. In this study we develop Monte Carlo ( MC) models for Ga desorption, in which the effects of the Al-Ga intera ction strength and the inclusion of an Al-Ga surface exchange mechanis m are investigated. The models which best describe the experimental ob servations are identified. The transients in Ga desorption rate at the AlGaAs-on-GaAs interface and the experimentally observed reduction in Ga desorption energy during growth of AlGaAs are explained in terms o f the reduction in V/III flux ratio accompanying the opening of the Al shutter. The proposed effects of this reduction in V/III flux ratio a re consistent with the results predicted by the different models.