SOFT-X-RAY PHOTOEMISSION-STUDIES OF S INP(100)/

High-resolution soft X-ray photoemission spectroscopy has been applied to study the clean and H2S-covered InP(100) surface. The clean surfac e is In-rich and forms a (4 x 2) reconstruction. The In 4d core levels and the P 2p levels show surface shifts which in general terms are co nsistent with existing models [1]. The P 2p level shows only a small s urface shift, suggesting that most atoms are in a bulk-like configurat ion. The In 4d peak shows three surface and subsurface peaks and one b ulk peak whose energies are extracted by fitting. When hydrogen sulphi de is adsorbed, and the surface then annealed, a single sulphur peak i s observed. The small shift of the P 2p core level is not changed sign ificantly in contrast with the In 4d surface peaks, which change their energy and relative intensity, indicating that the sulphur adsorbs pr edominantly on the metal sites.