EVOLUTION OF AUGER PEAKS IN GAP(110) WITH HYDROGEN CHEMISORPTION

Auger spectroscopy flanked by energy loss spectroscopy was used to inv estigate the evolution of GaP(110) surface electronic structure upon h ydrogen exposure. The paper is focussed on the modification of PL(2,3) VV Auger line shape as a function of hydrogen exposure in the exposure range between zero and Ga3d surface exciton quenching. The discussion is concentrated on the Auger emission region about 9 eV below the emi ssion from valence band top. The line shape change can be explained on the basis of present knowledge of electronic structure of H:GaP(110) surface and ascribed to the birth of a hydrogen-induced state (H-4) at similar to 4.4 eV below valence band top. Moreover the surface stoich iometry was monitored by Auger spectroscopy through the PL(2,3)VV to G aM(2,3)M(4,5)M(4,5) peak-to-peak ratio which was found to be extremely affected at high hydrogen exposures.