Site-Specific Densities of States for Cleaved and Sputtered GaAs (110) from Auger Line Shapes

摘要

The nature and extent of interfacial chemical reactions are major factors affecting the electronic properties of semiconductor-metal or semiconductor-semiconductor interfaces. There reactions and the resulting chemical phases may depend strongly on the surface structure and the extent and nature of structural defects. A first step to understanding defect-related chemical phase formation and interfaces is to correlate local chemical properties with structural defects. We have made an initial attempt to do this for GaAs (110) by comparing the results of several techniques. We have examined the cleaved and sputtered GaAs (110) surface with x-ray photoemission spectroscopy (XPS), Auger electron spectroscopy (AES) line shape analysis, low-energy electron diffraction (LEED), and scanning electron microscopy (SEM). In the Auger process, because the initial core hole is localized around one atom, the probability of exciting a valence electron in a core-core-valence transition falls off quite rapidly away from the core. Consequently, the charge distribution that is probed by such transitions is site-specific and may differ if the initial core hole is made on the anion or the cation. This is in contrast to a photoemission measurement, where sites widely separated in R may contribute to the photoelectron intensity at a particular value of energy.