A low temperature operated NO2 gas sensor based on TeO2/SnO2 p–n heterointerface

A novel sensor design structure comprises TeO2/SnO2 p–n heterointerface was fabricated using rf sputtering technique and has been successfully exploited for trace level (1–10 ppm) detection of NO2 gas at a much lower operating temperature of 90 °C. Integration of n-type SnO2 sensing layer with p-type TeO2 microdiscs (600 μm diameter) of an optimum thickness of 18 nm are found to enhance the sensing response (∼2.26 × 104) for 10 ppm of NO2 gas at a comparatively low operating temperature (90 °C) with a fast response speed (∼1.25 min). The improved sensing response characteristics of the heterointerface sensor structure are attributed to formation of p–n junctions at the interface of SnO2 with TeO2 microdiscs and modulation of the depletion width on interaction with the target NO2 gas. The origin of enhanced sensing mechanism of the heterointerface sensor has been discussed in details.