Nanoscale potential fluctuations and electron percolation in silicon oxide (SiOx, x=1.4, 1.6)

Abstract

Using the method of high-resolution x-ray photoelectron spectroscopy (XPS), the short order in the SiO1.4 film was studied. The random bonding (RB) and random mixture (RM) models do not describe the experimental spectra of SiO1.4. The intermediate model (IM) structure of SiO1.4, based on the local spatial fluctuations of the chemical composition, which leads to potential fluctuations for electrons and holes, is proposed. In a wide range of electric fields and temperatures, the current-voltage characteristics of SiOx films (x = 1.4, 1.6) were measured. The Efros-Shklovskii percolation theory was used for the description of SiOx conductance. The percolation energy values for electrons: 0.5 eV for SiO1.4 and 0.8 eV for SiO1.6 were obtained. Taking into account that the potential fluctuation amplitude for electrons is 2.6 eV, the spatial potential fluctuation estimates for them are 2.8 and 3.4 nm for x = 1.4 and 1.6, respectively.