Characterization of improved InSb interfaces

Improved quality surfaces on n-type InSb have been produced using a low-temperature chemical vapor deposition (LTCVD) of SiO2. Preservation of the thin, natural oxide on the InSb surface through a suitable process results in MIS devices with a surface state density < 10¹⁰eV^-1cm^-2without C-V hysteresis. These results are confirmed by conductance measurements on MIS samples. The chemical identification and thickness of the natural oxide both before and after the LTCVD process was determined by using AES and XPS techniques. These data show a change in the oxidation sate of In depending on the degree to which silane dissociation occurs on the oxide surface. The electrical results on MIS devices correlation with these differences; surface state density degrade to the middle to high 10¹¹eV^-1cm^-2range for the predominantly heterogeneous reaction resulting from a vertical CVD reactor. The C-V measurements are complicated by the presence of surface potential fluctuations caused by the granularity of the LTCVD oxide.