Composition and electronic properties of P-enriched InP (1 1 1)-Au interfaces

Atomically clean phosphorus-enriched InP (1 1 1) surfaces have been produced by argon sputtering and subsequent annealing in a phosphorus ambient. Surface Fermi-level pinning positions ranging from 0.70 to 1.10 eV above the valence-band maximum have been measured for both n- and p-type InP (1 1 1), depending on the exact annealing conditions. Photoemission spectra of core levels indicate no additional band bending as a function of gold coverage. These pinning positions anformation about the drift mobility or carrier lifetimes, but instead is governed by the contact depletion-layer capacitance and the bulk series resistance. Analysis of the results gives a new method of determining the density of shallow occupied states in a-Si:H and quantitative results are given for some n- and p-type samples. Measurements of gap-cell photoconductivity are shown to have similar contact effects which causes a decay artifact that can extend up to 1 sec. It is argued that the artifact may have been mistakenly interpreted as bulk dispersive transport and recombination in some published data.