Influence of radiofrequency power on structural, morphological, optical and electrical properties of magnetron sputtered CdO: Sm thin films as alternative TCO for optoelectronic applications

Abstract

Highly transparent and conducting samarium doped cadmium oxide (CdO: Sm) thin films were deposited on glass substrates at room temperature by radio frequency (RF) magnetron sputtering technique using CdO(90 wt%): Sm2O3(10 wt%) mixed alloy target in pure argon atmosphere. The influences of RF power and Sm incorporation on structural, morphological, optical and electrical properties of the films were investigated. X-ray diffraction analysis revealed that the deposited films are polycrystalline nature and RF power has a large impact on the preferred orientation of the films. The X-ray photoelectron spectroscopy studies confirmed the presence of divalent cadmium (Cd2+) and trivalent samarium (Sm3+) in the deposited film. It is found from the atomic force microscopic analysis that the films were highly smooth with low roughness value of about1.3 nm. High transmittance value greater than 80% was retained by the films in visible and near infrared regions and the band gap value decreased with the increase of RF power by quantum confinement. At the moderate RF power of 200 W, the film has low resistivity of the order of 1.283 × 10−4 Ω cm, high mobility 157.8 cm2/V and a high figure of merit 769.04 (Ω cm2)−1 which could be used as an alternative TCO layer for future optoelectronic devices.