Effects of Sn Doping on Properties of Multilayered ZnO Films Deposited by Spin Coating/Sol-Gel Method

The effects of the Sn doping density and multilayer deposition on the structural, optical, and electrical properties of ZnO films prepared by a spin coating/sol-gel method have been investigated. The film characteristics were studied using x-ray diffraction (XRD) analysis, electronic absorption (ultraviolet-visible) spectroscopy, atomic force microscopy, and measurements using the four-probe method. The XRD patterns of both the five- and ten-layered ZnO films confirmed Sn substitutional incorporation, where Sn4+ ions replace Zn2+ ions while preserving the hexagonal wurtzite structure. The results show that both the doping density and number of layers affect the crystallite size, film thickness, conductivity, and surface morphology, with films having doping densities of 1.5 at.% to 2 at.% showing preferred characteristics. Among the different films, the ten-layered film doped with 1.5 at.% Sn exhibited preferred properties in terms of root-mean-square surface roughness (5.1055 nm), average transmittance (93%), and notably conductivity (7.94 x 10(-3) omega(-1) cm(-1)).