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

Using the method of high-resolution x-ray photoelectron spectroscopy (XPS), the short order in the SiO_1.4 film was studied. The random bonding (RB) and random mixture (RM) models do not describe the experimental spectra of SiO_1.4. The intermediate model (IM) structure of SiO_1.4, 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 SiO_x films (x = 1.4, 1.6) were measured. The Efros-Shklovskii percolation theory was used for the description of SiO_x conductance. The percolation energy values for electrons: 0.5 eV for SiO_1.4 and 0.8 eV for SiO_1.6 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.