Origin of surface and metal-induced interface states in InP

Abstract

Surface states on $p$- and $n$-type InP UHV-cleaved (110) surfaces and chemically etched (100) surfaces have been determined with the use of surface photovoltage spectroscopy (SPS). No intrinsic surface states are found on cleaved or ion-bombarded surfaces. The origin of extrinsic surface states is attributed to compositional and stoichiometric variations identified by Auger-electron spectroscopy (AES). Chemical treatment, metal deposition, oxidation, and ${\mathrm{Ar}}^{+}$ bombardment of these surfaces produce a host of changes in the interface-state distribution within the InP band gap. Comparison of AES and SPS data from the various interfaces leads to explanation of the origin of the observed states and of their roles in determining interface electronic properties such as Fermi-energy-pinning positions.