Plasma Oxidized W-WOx Sensor for Sub-ppm H2S Detection

Abstract

In this work we have fabricated W-WOx core-shell nanowire structure using plasma oxidation, a CMOS compatible process, for sensing H2S gas. For comparison, the sputtered stack structure of W-WOx with different thickness ratios of W to WOx is fabricated and characterized for H2S sensing. The sensor fabricated using plasma oxidation process is found to be significantly better in sensing performance compared to the sensing results obtained from sensor fabricated using sputtering. The response of plasma oxidized sensor is 90.4% for 1 ppm H2S with response and recovery time of 4 s and 46 s respectively. In contrast, the sensor fabricated with sputtered film shows a response of 30.6% at 1 ppm with response and recovery times of 19 s and 84 s respectively. This study clearly indicates that plasma oxidation is an efficient method for development of stable sensors.