A cryogenic ultra-high vacuum scanning tunnelling microscope was used to study the electron-stimulated desorption of H and D from Si(100) surfaces at 11K. A marked isotope effect was observed, as noted previously at room temperature. In the tunnelling regime above about 5eV, the desorption yields for H and D were temperature-independent while, below 4eV, H was a factor of some 300 easier to desorb at 11K than at 300K. The large temperature dependence was explained in terms of a model that involved multiple vibrational excitation, and took account of an increase in the Si-H(D) vibrational lifetime at low temperatures.

Cryogenic UHV-STM Study of Hydrogen and Deuterium Desorption from Si(100). E.T.Foley, A.F.Kam, J.W.Lyding, P.Avouris: Physical Review Letters, 1998, 80[6], 1336-9