Selective H2S-sensing performance of Si nanowires through the formation of ZnO shells with Au functionalization

Abstract

A novel gas sensor fabricated from ZnO-shelled Si nanowires (SiNWs) is presented. After coating a thin layer of Au on the surfaces of Si NWs, ZnO layers were formed on the surfaces of p-SiNWs by thermal evaporation of Zn powders and a subsequent oxidation process. Microscopic analysis confirmed the successful formation of ZnO-Si core-shell NWs with Au nanoparticles present on the shell surface. The gas sensing performance of the gas sensor fabricated using the p-Si/n-ZnO core-shell NWs was evaluated for various gases. The sensor exhibited outstanding response and selectivity to H2S gas. The gas sensing mechanism was evaluated in detail and attributed to various factors, including the formation of ZnO/Si and Au/ZnO heterojunctions and the chemical attraction between ZnO and Au. The results demonstrate a new sensing material for H2S detection in various fields that can be easily incorporated into Si-based devices.