Influence of Sn dopant on ZnO Thin Film for Formaldehyde Detection

Abstract

In this work, structural, morphological, electrical and gas sensing of ZnO and Sn doped ZnO thin film at different atomic percentage (0.5at%, 1.0at% and 1.5at%) had been studied. The precursor was prepared by sol-gel method and deposited on an IDE glass substrate by using spin coating technique. The effects of the dopant was then characterized through XRD, AFM, SEM and Agilent LCR Meter. Based on the XRD results, it was found that all films showed the highest diffraction peak intensity at (002) with crystallite size in the range of 8-33nm. Meanwhile the morphological properties from AFM and SEM showed an improvement in surface roughness from 16.7nm to 5.48nm and decrease the grain size from 45.42nm to 40.99nm in the presence of Sn dopant. Based on the image, the grains were uniformly distributed and ZnO thin film showed the hexagonal wurtzite structure, which proved the XRD result. Among all the samples, 1.0at% Sn doped showed the best result for detection of formaldehyde at 0.6ppm which up to 96% compare to undoped, 26.04% at 150°C. The response and recovery time was between 4-16 seconds. This showed that the presence of Sn can help to improve the conductivity of the ZnO thin film.