Properties of SnO 2 films fabricated using a rectangular filtered vacuum arc plasma source

Abstract

Transparent and conducting SnO 2 films of 57–200nm thickness were deposited on microscope glass slide substrates, using a rectangular filtered vacuum arc deposition system. The 40 glass slides were equally distributed on a 400 × 420mm substrate carriage, and were exposed to a Sn plasma beam, produced by a rectangular vacuum arc plasma gun with a Sn cathode, and passed through a rectangular magnetic macroparticle filter towards the substrates. The carriage with the substrates was transported past the 94 × 494mm filter outlet. The SnO 2 films were fabricated on the glass substrates at room temperature by maintaining the chamber oxygen background pressure at 0.52Pa. The film composition, and electrical and optical properties were studied as a function of the film thickness. The films were stored under ambient air conditions, and their electrical resistance was measured as a function of storage time over a period of several months. The average resistivity of films was 10–17mΩ cm for films with thickness ( t) less than 100nm, but that of t > 100nm it was 5–9mΩ cm. The resistivity of the films with t > 100nm did not change significantly after 8months of storage in ambient air. The optical transmittance of the films in the visible spectrum was in the range of 75–90%. The optical constants, i.e., the refractive index and the extinction coefficient of the films at wavelength λ = 550nm were in the range of 2.02–2.09 and 0.013–0.023, respectively, and the optical band gap energy was 4.15–4.21eV. Unlike the electrical resistivity, the optical parameters weakly depended on t.