Lithium-antimony co-doping induced morphology transition in spray deposited SnO2 thin films

Abstract

Un-doped, Sb doped (ATO) and Li-Sb co-doped SnO2 (LATO) transparent conducting thin film electrodes have been deposited using facile spray pyrolysis method. X-ray diffraction study is carried out to confirm the crystal structure, phase purity, and textured growth of the films. Surface morphological transition from dendritic to cuboid shape is observed upon Li-Sb co-doping into the SnO2 system from the scanning microscopy measurements. The AFM analysis confirms that as Li doping concentration (1, 3, 5 wt.%) increases, the surface roughness of the films decreases. The UV-Vis transmittance spectra of the SnO2 film doped with 5 wt.% Li and 5 wt.% Sb (LATO5) shows maximum average transmittance of 87.9 % at 550 nm and the calculated direct band gap value is 4.06 eV. The LATO5 film exhibits high carrier concentration and high mobility of 7.54 × 1020 cm−3 and 7.221 cm2/Vs, respectively, due to co-dopant effect at the Sn sites of SnO2 lattice, resulting in enhanced electrical transport properties compared to un-doped SnO2 film. The LATO5 film also exhibits lowest sheet resistance of 32.38 Ω/□ and resistivity of 1.57 × 10−3 Ω cm. The temperature dependent electrical conductivity study is performed to understand the conduction mechanism of the film via estimation of activation energy from Arrhenius plots. The obtained results indicate that the Li-Sb co-doped SnO2 films are potential candidates for alternative transparent conducting electrode system.