InAs Nanowire Transistors as Gas Sensor and the Response Mechanism

We report a study of the response of InAs nanowire field-effect transistor sensor devices to various gases and alcoholic vapors. It is concluded that the change in conductance of the device in response to chemical vapors is a combined result of both the charge transfer and modified electron mobility effects. In particular, we found that surface adsorption of most chemical molecules can reduce electron density in nanowires from ∼104 to ∼103/μm and enhance the electron mobility greatly (from tens to a few hundred of cm2/(V s)) at the same time. These effects are attributed to the interactions between adsorbed molecules and the electron accumulation layer and rich surface states on the InAs nanowire surface.