Chemical alteration of the native oxide layer on LiGaO2(001) by exposure to hyperthermal atomic hydrogen

X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) have been used to examine the near-surface region and outermost atomic layer of air-exposed, solvent-cleaned, LiGaO2(001) substrates, respectively, before and after room-temperature exposures to the flux produced by a novel electron stimulated desorption hyperthermal H-atom source. The native oxide layer on the solvent-cleaned LiGaO2(001) substrate is nonhomogeneous and contains primarily LiO, Ga, and small amounts of C. Li is initially present in the near-surface region as Li2O, LiGaO2, and a small amount of LiOH. Several forms of O are present including adsorbed water, LiGaO2, Li, and Ga-oxides, and hydroxyl groups with Ga2O3 as the predominant species. Upon exposure to the: hyperthermal H-atom flux, low-temperature removal of oxygen and carbon contaminants occurs, and the near-surface region approaches the stoichiometry of a clean LiGaO2(001) surface except for an increased O concentration. The usually difficult to observe Li 1s photoelectron peak increases in intensity significantly with H-atom exposure. XPS binding energies for LiGaI2(001) have been assigned for Li 1s, O 1s, Ga 3d, and 2p peaks at 56.0, 530.2, 19.4, and 1116.9 eV, respectively. According to the Het ISS data, the H-atom flux is very effective in removing surface contamination and enriches the outermost atomic layer in O through diffusion of subsurface O to the surface under a chemically induced driving potential. This O enrichment implies that the diffusion of O to the surface is more rapid than removal of surface O by impinging H atoms. (C) 1998 American Vacuum Society. [S0734-2101(98) 05406-2].