Stable clusters array of silicon nanowires developed by top-plating technique as a high-performance gas sensor

Abstract

For a gas sensor based on aligned nanowires array, effective extraction of sensing signals produced by all of nanowires is extremely crucial to harvest high response magnitude. In this work, a stable clusters array of silicon nanowires arrays (SiNWs) with a unique aggregation interconnection (AI) configuration was proposed to boost the sensing performances of the corresponding sensor. The stable AI structure was achieved by Cu2O top-plating technique via multiple spin-coating of Cu2+ and HF solution on SiNWs. The top-plating treatment produces a unique and stable clusters array of vertical SiNWs with obvious tip AI structure of nanowires in different clusters. And the as-formed AI array is proved to be highly effective as a gas sensor in achieving highly sensitive and stable response and low detection limit at room temperature. Compared with the pristine SiNWs sensor, the AI-SiNWs sensor displayed ~64-fold enhancement in response value to 1 ppm NO2, and the limit detection concentration of NO2 gas deducted by the experiment data is 5.4 ppb. The satisfactory sensing-performances can be interpreted effectively in terms of the effectiveness of the unique AI array in extraction of electronic response signal of SiNWs sensing units and reduction of substrate resistance influence from Cu2O soldering.