Chemical trapping and modification of the Au/GaAs(110) interface using Sm interlayers

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Abstract
We present high-resolution synchrotron-radiation core-level photoemission results which reveal the evolving electronic structure and morphology of the Au/GaAs(110) interface with ultrathin interlayers of Sm (4–30 Å). Although the Sm/GaAs interface is among the most reactive metal-III-V-semiconductor interfaces studied to date, our core-level results indicate that the deposition of Au over Sm/GaAs induces Ga and As redistribution. In particular, Ga and As atoms which are found in solid solution in the Sm interlayer region can be extracted into the Au overlayer as Au reacts with Sm to form an intermetallic. In contrast, As atoms which have formed compounds with Sm are trapped at the interface. The resulting interface is then highly heterogeneous both laterally and vertically. Our results show that the evolution of the interface and the atomic distribution across the Au/Sm/GaAs system thus critically depends on the Sm interlayer thickness. Thermochemical data pertaining to the possible compounds and solid solutions which can form in the interface region are used together with photoemission results to model the interface and establish general trends in metal-GaAs interface development.