Reactivity studies and structural properties of Al on compound semiconductor surfaces

The authors studied the structural properties of Al on III-V semiconductors (InAs, GaAs, and InGaAs) with the aim of creating smooth and abrupt interfaces. Growth conditions, such as the residual As content and the presence of intermediate layers, affect the structural properties of the Al and the underlying semiconductor. The authors find that an ultrathin layer of AlAs on (001) InAs drastically reduces the interface reaction and improves the epitaxial growth of Al. No such layer is necessary for interface reaction mitigation for Al deposited onto InGaAs or GaAs. The crystal orientation of Al planes grown on (001) InAs is [110], but is [111] on InGaAs or GaAs. The authors discuss the significance of the results for realization of structures for proximity superconductivity.