RESIDUAL GAP SURFACE-STATES ALONG VARIOUSLY HYDROGENATED SILICON(111)AND SILICON(100) SURFACES

Different H-saturated silicon surfaces have been studied by low-energy electron diffraction and photoemission yield spectroscopy, Hydrogenat ion was performed in ultrahigh vacuum (UHV) with an atomic H flux upon a Si(100)-(2 x 1) surface either at room temperature or at 350 degree s C, and upon cleaved (2 x 1) or (7 x 7) Si(111) surfaces. H-saturated Si(111) was also achieved via a chemical treatment prior its introduc tion into UHV. Analysis of the PYS curves shows that these surfaces bo th show scattering effects and contain residual surface-state densitie s in the gap which strongly depend on the surface and on the hydrogena tion procedure. The chemically hydrogenated Si(111) surfaces are the s moothest at the atomic scale, as proved by the lowest gap state densit y and the least surface scattering effects.