Study of NO2 gas sensing at low temperature based on the incorporation of silicon nanostructures with tungsten trioxide nanoparticles

Abstract

The sensing behavior of semiconductor gas sensor is usually based on the measurement of the resistance change caused by the gas molecules adsorbed on the material and reacts with the oxygen ions on the surface of the material to indicate their sensitivity (response) to a certain gas In this study the WO3 NPs@SiNWs WO3 NPs@porous Si and WO3 NPs@curved SiNWs composite are prepared to detect 3 ppm NO2 gas at room temperature WO3 an n-type material has high selectivity for the detection of NO2 gas The different morphology of silicon nanostructure was made by metal-assisted chemical etching (MaCE) and electric-field assisted MaCE (EMaCE) The mechanism of hole diffusion and the changes of silicon nanostructure morphology with or without applying bias are illustrated and ability of controlling the formation of the nanostructures is demonstrated In addition the curved SiNWs can be prepared through Au/Ag co-catalyst and HNO3 etching WO3 is synthesized on the silicon nanostructure through a novel hydrothermal method After WO3@Si samples are prepared samples will be treated with oxygen plasma to increase surface defect concentration for enhancing gas sensing response Among the three samples mentioned above WO3 NPs@curved SiNWs modified by oxygen plasma shows excellent response 3 49 to 3 ppm NO2 gas at room temperature

Date of Award	2020
Original language	English
Supervisor	Chia-Yun Chen (Supervisor)