Electronic structure and nanoscale potential fluctuations in strongly nonstoichiometric PECVD SiOx

Abstract

The electronic structures of SiOx:H films synthesized by plasma-enhanced chemical vapor deposition on silicon and glass substrates were studied. The film stoichiometric parameter x varied in the range from 0.57 to 2 depending on the oxygen supply to the reactor conditions. According to XPS, Raman scattering and high-resolution electron microscopy, a core-shell model of the a-SiOx:H structure was applied. According to this model, the films consist of silicon suboxide SiOy, in which clusters of different compositions are introduced — from amorphous silicon to silicon oxide — with a characteristic size of 2–10 nm. The SiOx:H energy diagram was constructed. The nanoscale potential fluctuations model, according to which Si nanoclusters are potential wells for electrons and holes in SiOx, is proposed. The data obtained are important for the correct interpretation of the charge transport in a-SiOx:H films, and they are important for the development of nonvolatile memory elements on their basis.