Arsenic- and metal-induced GaAs interface states by low-energy cathodoluminescence spectroscopy

We used optical emission techniques to obtain a direct measure of discrete electronic states at GaAs interfaces. These states depend on surface preparation, metallization, and semiconductor material. The energy of the discrete states found at metal/molecular-beam epitaxially grown GaAs(100) interfaces integrated within a Schottky formalism provides self-consistent results for the interface electrostatics. The presence of a large concentration of extrinsic defects causes the pinning behavior observed at metal/melt-grown GaAs(110) interfaces. These results provide the first direct experimental evidence for the origin of Fermi level ‘‘pinning’’ at metal/melt-grown GaAs junctions.