Atomistic view of the recombinative desorption of H(2) from H/Si(100)

Abstract

Scanning tunneling microscopy is employed to investigate the recombinative desorption of H(2) from hydrogenated Si(100) surfaces consisting of dihydride (SiH(2)) and monohydride (SiH) surface species organized in (1x1), (3x1), and (2x1) configurations. The results show that desorption from dihydrides involves a pair of neighboring dihydrides linked along the tetrahedral bond direction. Dihydrides in (3x1) domains are separated in the same direction by monohydrides, and desorption from a pair is geometrically impossible. The same desorption mechanism nevertheless applies via first a position switching of dihydrides with neighboring monohydrides.