High sensitive room temperature NO2 gas sensor based on the avalanche breakdown induced by Schottky junction in TiO2-Sn3O4 nanoheterojunctions

Abstract

A novel sensor based on Schottky junction inducing avalanche breakdown effect in TiO 2 -Sn 3 O 4 nanoheterojunctions is assembled. High sensitivity for NO 2 gas sensing is demonstrated at room temperature. TiO 2 -Sn 3 O 4 nanocompositewas synthesized as the gas sensing layer and Schottky contact was formed by Au electrodes. The Schottky contact functions as a “gate” which can trigger the avalanche breakdown effect in the TiO 2 -Sn 3 O 4 heterojunctions. By tuning the Schottky barrier height through the responsive variation of the surface chemisorbed gas and the bias on the device, NO 2 at a concentration from 5 to 50 ppm can be detected with an average response time of 8 s at room temperature. This nanostructured device is a promising candidate for application in high-sensitivity and high-speed NO 2 gas sensor. The methodology and working principle illustrated in this paper present a new sensing mechanism that can be readily and extensively applied to other gas sensing systems. • TiO 2 -Sn 3 O 4 heterostructure was designed and synthesized in order to detect NO 2 gas in room temperature. • Avalanche breakdown effect was used to obtain 900% responsivity when exposed to 50 ppm NO 2 at room temperature. • High sensitivity and excellent selectivity to NO 2 is obtained at room temperature.