Ultra-high sensitive NO2 gas sensor based on tunable polarity transport in CVD-WS2/IGZO p-N heterojunction.

Abstract

In this work, thin-film transistor (TFT) gas sensor based on p-N heterojunction is fabricated by stacking chemical vapor deposition (CVD)-grown tungsten disulfide (WS2) with sputtered indium-gallium-zinc-oxide (IGZO) film. To the best of our knowledge, the present device has the best NO2 gas sensor response comparing to all the gas sensors based on transition metal dichalcogenides (TMDCs) materials. The gas sensing response is investigated under different NO2 concentrations, adopting heterojunction device mode and a transistor mode. High sensing response is obtained of p-N diode in the range of 1-300 ppm with receptivity associated sensitivity values of 230% for 5 ppm and 18170% for 300 ppm. On the transistor mode, the gas sensing response can be modulated by the gate bias, the transistor shows an ultra-high response after exposure to NO2, with sensitivity values of 6820% for 5 ppm and 499400% for 300 ppm. Interestingly, the transistor has a typical ambipolar-behaviour under dry air, while the transistor becomes p-type as the amount of NO2 increases. The assembly of these results demonstrates that the WS2/IGZO device is a promising platform for the NO2 gas detection, and its gas-modulated transistor properties show a potential application in tunable engineering for 2D materials heterojunction-based transistor device.