Electron stimulated desorption of negative and positive hydrogen ions from hydrogenated silicon surfaces.

Abstract

Electron-stimulated desorption of negative and positive hydrogen ions from hydrogenated amorphous silicon (a-Si:H) surfaces has been studied as a function of incident electron energy. Well-defined thresholds for emitted ions are observed at electron energies close to Si core-level binding energies, suggesting that the core-level electronic transitions are most likely responsible for emission of both negative and positive hydrogen ions. In addition to thresholds, the negative-ion yield, studied from both a-Si:H and hydrogenated ${\mathrm{SiO}}_{2}$ surfaces, exhibits some resonantlike features, indicating that some other, multistep channels for negative-ion desorption may also be activated. It has been also suggested that negative-ion formation may follow emission of secondary electrons. \textcopyright{} 1996 The American Physical Society.