REACTION OF HYDROGEN WITH INP(100)4X2 - SURFACE-PROPERTIES

For ion bombarded and annealed In-rich InP(100)4x2 we observed with hi gh resolution electron energy loss spectroscopy (HREELS) for the first time - besides the commonly reported surface optical phonon at 42 meV - an interface plasmon at 93 meV, due to high S doping (1 x 10(19) cm (-3)). Sequential hydrogenation results in the formation of metallic I n droplets; these increase in size and concentration with increasing h ydrogen exposure. The 4x2 pattern, measured by low energy electron dif fraction (LEED), changes from 4x2 to 4x1, and to 1x1. Finally a stage is reached where no pattern occurs. The change in surface morphology c hanges the full width at half maximum (FWHM) of the quasielastic peak - as measured with HREELS - dramatically. Owing to carrier compensatio n it increases initially and then decreases as a result of the metalli zation of the InP surface. Structure models for these observations are discussed.