Sn doped ZnO thin film for formaldehyde detection

Abstract

In this work, sol-gel with spin coating technique was applied in order to produce undoped and Sn doped ZnO thin film with different doping concentration of 0.5 at%, 1.0at% and 1.5at%. The starter material used was zinc acetate dehydrate (Zn(CH3COO)22H2O). The thin film was deposited on an interdigitated electrodes (IDE) for 5 hours and annealed at the temperatue of 500°C. The crystallite size of the film decreased when dopant was introduced, as well as the surface roughness of the thin film. XRD was used to identify the crystallinity, crystallographic orientation and phase evaluation of undoped and Sn doped ZnO. From the XRD pattern, it was observed that the peaks and diffraction correspond to the wurtzite-structured of ZnO. Sensing results indicate that the gas sensing response increase from undoped to doped ZnO thin film as a function of operating temperature where the maximum response for formaldehyde detection was at 130°C (∼95%) for doping concentration of 1.5at%. The response time for 0.4ppm of formaldehyde was 17sec followed with 16sec, 12sec and 13 sec for 0.6ppm, 0.8ppm and 1.0ppm respectively.