Sputtering Power and Annealing Effects on the Properties of Zn2SnO4–SnO2 Composite Thin Film for Pungent Smelling Gas (NH3) Detection

Abstract

A sputtering target of Zn2SnO4–SnO2 composite is prepared by mixing ZnO and SnO2 powder in the ratio of 1:1. Thin films of Zn2SnO4–SnO2 composite are prepared by radio frequency (RF) magnetron sputtering on quartz substrate with the sputtering power of 50, 100, and 150 W. The prepared films are further annealed at 500 and 1000 °C. The crystalline nature of the films is obtained after annealing at 1000 °C. Energy dispersive X‐ray (EDX) analysis and X‐ray photoelectron spectroscopic (XPS) study witness the compositional purity of the films. The scanning electron microscope (SEM) study shows that the as‐deposited films are smooth and crack free in nature. The transmittance of the film is enhanced due to annealing; the energy bandgap value is also increased with the increase in annealing temperature. The photoluminescence emission peaks are aroused due to the defect energy levels within the bandgap and oxygen vacancies. The activation energy of the film is decreased with the increase in annealing temperature. The gas sensing study of the Zn2SnO4–SnO2 composite film prepared with RF sputtering power of 150 W after annealing at 1000 °C shows an excellent sensing toward NH3 gas at room temperature with highest sensing response of 1897.