Realization of a Self-Powered InGaZnO MSM Ozone Sensor via a Surface State Modulated Photovoltaic Effect

Traditional gas sensors require an external voltage to provide a readout signal for measuring the resistance/current changes. To reduce the power consumption and working area for system-on-chip applications, photovoltaic self-powered gas sensors are a promising strategy. However, most of the reported self-powered gas sensors are based on a vertical p–n junction structure with two different electrodes located on opposite sides, which is incompatible with planar circuit technology. In this study, a metal–semiconductor–metal (MSM) self-powered ozone (O3) gas sensor based on a-IGZO is successfully fabricated using localized ultraviolet treatment (UVT) which is used to selectively modify the surface states underneath different contacts. The established asymmetric Schottky barrier results in self-powered characteristics under UV illumination. The self-powered gas sensor exhibits an unbiased gas response of 74% with a response/recovery time of 168/522 s toward 5 ppm of O3 at room temperature. The proposed method provides insights for easy fabrication of photovoltaic self-powered gas sensors using a highly integrated MSM structure.