SURFACE ELECTRONIC-STRUCTURE OF GAAS(110) STUDIED BY AUGER PHOTOELECTRON COINCIDENCE SPECTROSCOPY

Auger photoelectron coincidence spectroscopy has been used to study the M4,5 VV Auger spectra of GaAs(110). Using this technique, the Ga and As spectra can be separated and studied independently. The line shape of the As-M4,5 VV measured in coincidence with the As 3d photoemission line differs significantly from the conventional Auger spectrum. This is attributed to the surface electronic properties of the system. In addition, it is found that the ss component of the As spectrum is more intense than expected based on calculations using atomic matrix elements. The Ga-M4,5 VV spectrum, of which only the pp component is observed, agrees well with that expected from an independent electron model. A first principles electronic structure calculation of a five-layer GaAs(110) slab has been performed to aid in the interpretation of the Auger spectra.