MODIFICATIONS OF GaAs SURFACE UNDER Au EVAPORATING FLOW

摘要

Au films thermally deposited in vacuum differ from pure Au. New compounds, such as Au_3Ga, Au,Ga_2, are formed in this case, and Ga and As appear in the Au surface layer. In this work the GaAs surface state was investigated with surface acoustic waves in situ during thermal deposition of gold. The changes of the aggregate state caused by formation of the Au-Ga liquid phase followed by the creation of the solid solutions based on the Au_3Ga and the Au_7Ga_2 compounds are observed. Such transformations in the films seem to be determined by the diffusion of "free" (non-incorporated into the crystalline lattice) Ga and As atoms towards the GaAs surface due to the plastic deformation induced by the flow of thermally evaporated Au. Data is confirmed by the precise chemical analysis and Auger-spectroscopy.