Role of rf power on the properties of undoped SnOx films deposited by rf-PERTE at low substrate temperature

Transparent and conductive undoped tin oxide (SnOx) thin films were deposited at low substrate temperature (< 140 °C) by radio frequency (rf) plasma enhanced reactive thermal evaporation (rf-PERTE) of tin (Sn) in the presence of oxygen The undoped SnOx films were not submitted to any post-annealing treatments. The influence of rf power variation on the optical, electrical and structural properties of the as-grown films is presented. A variation in the films' structure was verified with the increase of rf power. Undoped SnOx films, 90 nm average thick, deposited at rf power range of 60–70 W are nanocrystalline, show a conductive behaviour, an average visible transmittance of ≥ 80% and a maximum electrical conductivity of about 34.6 (Ω cm)− 1. Films deposited at lower values of rf power (40 W) are amorphous and exhibit a semiconductive behaviour, showing an electrical conductivity of about 7.54 × 10− 1 (Ω cm)− 1. As a low substrate temperature deposition process is used, SnOx thin films can be obtained on a wide range of substrates.