Characterization of CuO-doped tin dioxide thin films prepared by pulsed-laser deposition for gas-sensing applications

Abstract

The influence of doping level of tin oxide films with different amounts of CuO additives (5%, 10%, 15%, and 20%) on structural, optical, and electrical properties is investigated. The films were prepared by pulsed-laser deposition method. X-ray diffraction patterns show the polycrystalline structure for all films with tetragonal phase for SnO2 and monoclinic phase for CuO, and no reaction between them. The surface morphology of films was analyzed and it revealed nano-sized grains for samples doped with 10% and 15% CuO. Hall’s effect measurements show increasing conductivity with increase in the CuO ratio and transfer the type of charge carriers from n- to p-type with 20% CuO. The H2S sensing properties are influenced by the CuO ratio in the SnO2 films as well as the operation temperature. The SnO2 sensor loaded with 10% CuO is extremely sensitive to H2S and the best operation temperature is 50°C, and it exhibits fast response speed of 7 s and recovery time of 20 s for trace level (10 ppm) H2S gas detection.