Correlation of Fermi-level energy and chemistry at InP(100) interfaces

X-ray photoemission spectroscopy data are used to correlate the interface Fermi-level pinning energy EiF and the corresponding interface chemistry for n-type and p-type InP (100) samples simultaneously subjected to a series of surface treatments. Interfaces of Schottky-barrier contacts formed during a sequence of Au and of Al depositions made both onto chemically etched and thermally cleaned InP surfaces were investigated. Changes in EiF of up to ∼0.6 eV in the upper half of the InP band gap occurred in response to changes in interface chemistry. The observed behavior of EiF is interpreted in terms of a single defect model with multiple charge states.