Room-temperature operation of light-assisted NO ₂ gas sensor based on GaN nanowires and graphene

Abstract

Abstract We report the successful demonstration of a light-assisted NO 2 gas sensor that operates at room temperature with high response. The gas sensor was fabricated with high-crystalline undoped-GaN nanowires (NWs) and graphene functioning as the light-absorbing medium and carrier channel, respectively. Exposure of the gas sensor to the NO 2 concentration of 100 ppm at a light intensity of 1 mW cm −2 of a xenon lamp delivered a response of 16% at room temperature, which increased to 23% when the light intensity increased to 100 mW cm −2 . This value is higher than those previously reported for GaN-based NO 2 gas sensors operating at room temperature. The room-temperature response of the gas sensor measured after six months was calculated to be 21.9%, which corresponds to 95% compared to the value obtained immediately after fabricating the devices. The response of the gas sensor after independently injecting NO 2 , H 2 S, H 2 , CO, and CH 3 CHO gases were measured to be 23, 5, 2.6, 2.2, and 1.7%, respectively. These results indicate that the gas sensor using GaN NWs and graphene provides high response, long-term stability, and good selectivity to NO 2 gas at room temperature. In addition, the use of undoped-GaN NWs without using additional catalysts makes it possible to fabricate gas sensors that operate at room temperature simpler and better than conventional technologies.

Topics & Concepts