Optical and structural properties of Sn doped ZnO thin films synthesized by spray pyrolysis

The zinc oxide (ZnO) thin films doped with tin (Sn) were deposited on the quartz and silicon substrates using ultrasound spray pyrolysis. The effect of Sn doping on structural and optical properties was investigated in ZnO films with Sn contents of 1.0, 2.0 and 3.0 at%. The analysis of XRD patterns of ZnO films confirmed the wurtzite crystal structure with a preferential growth along c axis. Furthermore, a significant shift in the position of XRD peaks versus Sn contents, indicating a change in the lattice parameters a and c due to the incorporation of Sn ions in the crystal structure. The SEM images show the dependence of the shape and size of hexagonal form grains on Sn doping levels. The transmittance study was applied to the estimation of the optical band gap of ZnO:Sn thin films. A small blue shift of bandgap energy was detected with increasing the Sn content.