Atomic-scale conversion of clean Si(111):H-1×1 to Si(111)-2×1 by electron-stimulated desorption

Tunneling images of the ideal Si(111):H-1×1 surface exhibit features and electronic structure consistent with a simple termination of the surface dangling bonds by atomic hydrogen. Bombardment of the surface with low-energy (2–10 eV) electrons desorbs the hydrogen, converting the 1×1 surface phase to the 2×1 π-bonded chain. The efficiency of this process versus electron kinetic energy indicates that the desorption is mediated by promoting electrons from the σ to the ${\mathrm{\sigma }}^{\mathrm{*}}$ band. The resultant increase in surface free energy drives a spontaneous phase transition to the 2×1. Individual 2×1 regions as small as ten surface sites have been created in this fashion.