Argon pressure dependent optoelectronic characteristics of amorphous tin oxide thin films obtained by non-reactive RF sputtering process

Abstract

In this work, amorphous tin oxide thin films were deposited by non-reactive radio frequency magnetron sputtering. A ceramic $${\text{SnO}}_2$$ target was used, while different working pressures were employed. The target to substrate distance was fixed to 17 cm, and the substrate was not intentionally heated. The properties of $${\text{SnO}}_2$$ (thickness, refractive index dispersion, optical band gap, resistivity, free carriers concentration, carriers mobility, carriers majority type and their scattering time) have been inferred from spectroscopic ellipsometry, conventional UV-Vis spectroscopy and specific Hall electrical measurements. Thickness and refractive index are slightly dependent on the deposition conditions, while the optical band gap, free carriers concentration and their mobilities are changing from sample to sample. The evolution of the optical band gap and carriers concentration is correlated to the active defects concentration. Amorphous $${\text{SnO}}_2$$ films grown at 0.4 Pa have the lowest resistivity of $$0.86\,\Omega \, \hbox {cm}$$ , a carrier concentration of $$1.05 \times 10^{18}\,\hbox {cm}^{-3}$$ , and a Hall mobility of $$6.8\,\hbox {cm}^{2}$$ / Vs. The average optical transmittance in visible spectrum is 76%.