Studies of Au-GaAs (001) interfaces prepared by molecular beam epitaxy. II. Thermal stability of Au-GaAs (001) interface

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Abstract
Au/GaAs (001) interface reactions due to annealing have been studied using the XPS, RHEED, SEM, RBS, EPMA, and AES methods. The samples were prepared by Au deposition on MBE-grown GaAs (001)-c(4×4) surfaces at room temperature. The Au films were epitaxially grown twin crystals, about 50 Å thick. Two phenomena were observed: Au shrinkage and erosion of GaAs by Au. The Au shrinkage occurs in the early stage of annealing. Rectangular or connected rectangular GaAs surfaces are exposed due to Au shrinkage. The sides of these rectangular surfaces are parallel to the GaAs 〈110〉 and 〈1̄10〉 directions. The higher the annealing temperatures, the greater the Au shrinkage and erosion of GaAs by Au. For the sample annealed at 450 °C for 3 h, Au-Ga alloy agglomerates formed on the GaAs (001) and GaAs (111) B surface. The one-dimensional disordered structure was observed by RHEED for the sample annealed at 305 °C for 14 h. The Au crystal quality is improved by annealing at temperatures above 100 °C.