CRYOGENIC UHV-STM STUDY OF HYDROGEN AND DEUTERIUM DESORPTION FROM SI(100)

A cryogenic UHV scanning tunneling microscope has been used to study t he electron stimulated desorption of hydrogen and deuterium from Si(10 0) surfaces at 11 K. A strong isotope effect is observed, as seen prev iously at room temperature. Above similar to 5 eV, the desorption yiel ds for H and D are temperature independent, while in the tunneling reg ime, below 4 eV, H is a factor of similar to 300 easier to desorb at 1 1 than at 300 K. This large temperature dependence is explained by a m odel that involves multiple vibrational lifetime at low temperature.