XPS VALENCE BAND STUDIES OF THE BONDING CHEMISTRY OF GERMANIUM OXIDES AND RELATED SYSTEMS

XPS generated valence band spectra have been employed to analyze the surface characteristics of several germanium oxide systems. A sputter deposited material with [O/Ge] almost-equal-to 2.0 is shown to be primarily GeO2. The covalency/ionicity of the latter is compared to other Group IVA oxides. Shoulder peaks detected deep in the band gap, in a region where such states as E' and F centers have been proposed, are attributed to discrete oxygen defects. The latter were dramatically enhanced by select Ar+ ion beam alteration. During the production of these defects, a suboxide, primarily classified as Ge(II)O, was also created. Reinvestment of oxygen established that the latter is not part of the aforementioned oxygen defect. Shifts in the occupied density of states of GeO2 suggest that the GeO system may be characterized by the presence of pi-bonding. Analysis of a Ge-degrees sample does not suggest its significant production during the previously described processes.