Performance improvement of nitrogen dioxide gas sensors based on novel p-n heterojunction gold black/VOx bi-sensing membranes

摘要

In this work, novel NO2 gas sensors having p-n heterojunction bi-sensing membranes obtained using gold black/VOx films were developed. VOx and gold black films were sequentially deposited on quartz substrates through radio frequency magnetron sputtering system and low-temperature vapor cooling condensation system, respectively. Scanning electron microscopy and atomic force microscopy images revealed that a rougher surface was obtained for gold black/VOx bi-sensing membranes than for VOx sensing membranes. After the detection of NO2 gas by using an NO2 gas sensor with a gold black sensing membrane and another with a VOx sensing membrane, results confirmed that the p-n heterojunction could be formed using gold black/VOx bi-sensing membranes. Because of a large surface area-to-volume ratio and the formation of the p-n junction of gold black/VOx bi-sensing membranes, the gas response of prepared NO2 gas sensors was improved from 78.78% to 188.15% compared with NO2 gas sensors with VOx membranes operated under 100 ppm NO2 concentration at its respectively optimal operating temperature. Furthermore, in NO2 gas sensors with gold black/VOx bi-sensing membranes, a minimum NO2 concentration of 1 ppm could be detected.