Interplay of the monohydride phase and a newly discovered dihydride phase in chemisorption of H on Si(100)2 × 1

Abstract

We have established that chemisorption of atomic hydrogen on Si(100) forms a previously unreported dihydride phase, Si(100)1 \ifmmode\times\else\texttimes\fi{} 1::2H, as well as the monohydride phase Si(100)2 \ifmmode\times\else\texttimes\fi{} 1:H. The interplay of these phases as exposure and temperature are varied casts new light on surface structure and bonding, and on the kinetics of thermal desorption. These studies suggest that the reconstruction inherent in the clean Si(100)2\ifmmode\times\else\texttimes\fi{} 1 surface is achieved by the pairing of adjacent surface rows (pairing model) rather than by surface vacancies (vacancy model).