InAs/InP core/shell nanowire gas sensor: Effects of InP shell on sensitivity and long-term stability

摘要

Long-term stability is an issue for semiconductor gas sensors, because the sensing material normally needs to be exposed to ambient air (oxygen and water molecules). InAs nanowires (NWs) feature good gas sensing properties at room temperature, but the NWs can be oxidized in air. In this paper, the gas sensing properties of InAs/InP core/shell NWs were investigated for the first time. It was demonstrated that the InP shell thicker than 3.3 nm can effectively retard the oxidation of InAs NWs in air for about 6 years. Moreover, the sensitivity can also be improved by introducing an InP shell. In comparison with the bare InAs NWs, similar to 1000 fold improvement on detection limit (i.e., 0.8 ppb NO2 at room temperature) was realized with an InP shell thicker than 3.3 nm. Related sensing mechanism is discussed.