Electron transport and defect structure in highly conducting reactively sputtered ultrathin tin oxide films

Abstract

Electrical conduction behavior of ultrathin (5–110 nm) SnO2 films reactively sputtered at 150–400 °C substrate temperatures is presented. The surface roughness studies revealed that the films with lower thickness were smoother (≤0.6 nm). Stoichiometry/defect structure of the films obtained from X-ray photoelectron spectroscopy data and electron mobility are found to be dependent on film thickness and substrate temperature. The observed increase in conductivity of semi-metallic films with decrease in film thickness is attributed to changes in defect structure and surface roughness. Highest value of conductivity of about 715 Ω−1 cm−1 is obtained for 5 nm thick films deposited at 300 °C.