Electron-stimulated bond rearrangements on the H/Si(100)-3×1 surface

Rearrangements of the Si(100)-3×1:H surface induced by an STM tip at a positive sample bias are examined. Emphasis is placed on local 3×1→2×1 restructuring of the surface following the loss of two H atoms. The H-atom desorption yield from monohydride sites of the 3×1 surface and the 3×1→2×1 transition yield induced by electronic excitation are presented. Based on electronic structure calculations, it is estimated that the 3×1→2×1 rearrangement process has overall barriers ranging from 0.1 to 1.6 eV, depending on the sites from which the H atoms are lost. It is proposed that STM-induced vibrational excitation of surface bonds provides the energy for surmounting the rearrangement barriers.