Room Temperature Operable Semiconducting Metal Oxide Chemi-Resistive NO2 Gas Sensor

Abstract

The quest for the room temperature operable semiconducting metal oxide gas sensors has come to an end. We fabricated an InGaZnO based chemi-resistive gas sensor, which is remarkably sensitive and selective to NO2 gas. Conventional semiconducting metal oxide gas sensors are active at high temperatures or in presence of light, which makes them power-hungry. The fabricated sensor is room temperature operable and requires light only to regenerate the device after exposure. NO2 has adverse effects on human health at concentration as low as 2 ppm. The measured limit of detection of the sensor is 100 ppb. Comprehensive NO2 adsorption studies were performed using kelvin probe force microscopy (KPFM) and X-ray photoelectron spectroscopy (XPS). The detailed mechanism of sensing and reviving is proposed. The fabricated sensor is compatible with CMOS process and can be integrated with the CMOS circuitry to make compact sensing system.