A stable germanium oxide is formed by depositing a SiO2 film, by chemical vapor deposition (CVD), on a germanium substrate and annealing in oxygen. Auger electron spectra for this stable germanium oxide are presented. The chemical shifts and the new transitions due to oxidation are shown for some major peaks, e.g., for transitions M45N23N23 the energy shifted from 22.5 to 18 eV, and for L1L3M45 from 106 to 101.5 eV. The energy shifts and new transitions in Auger peaks of a thermally oxidized sample are used to establish the presence of germanium oxide in between the SiO2 and Ge due to the oxidation annealings. The profiles of forming gas-annealed and argon-annealed samples are shown to contain very little oxidized Ge. The reduction of interface state density of Ge metal–insulator–semiconductor (MIS) structures when annealed in O is probably due to the oxidation of Ge (and reduction of dissolved hydrogen) which reduces the defects originally present in the interface region following SiO2 deposition.