Ion-bombardment induced light emission from Si(1Â 0Â 0) surfaces under continuous germane exposures

The intensities of the optical spectral lines emitted from a Si(1 0 0) surface under Ar+ ion bombardment are studied as a function of the ion kinetic energy (1-5 keV) and the partial pressure of germane. In these experiments, the ion flux is held constant while either the bombardment energy or the partial pressure of germane is varied. The excited neutral Si (SiI, 288 nm), neutral Ge (GeI, 265 nm and 304 nm), H Balmer beta (486 nm) and H Balmer gamma (434 nm) optical lines are observed. With increasing germane partial pressure, a broad emission feature develops between 330 and 365 nm and is assigned to excited GeH2 and/or GeH3 species. The emission intensities of the excited neutral Si, neutral Ge, Hβ and Hγ optical lines from the bombarded Si(1 0 0) surface increase with greater germane partial pressures and ion kinetic energy in a manner similar to that previously observed for silane exposures. In contrast to the monotonic increase of the above emission lines with higher germane partial pressures and greater incident kinetic energies, the H Balmer alpha (656 nm) optical line exhibits unique behavior. Paralleling the behavior observed for silane exposed surfaces, the intensity of the Balmer alpha transition decreases with increasing incident ion kinetic energy at all measured partial pressures of germane.