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 approximately 10(4) to approximately 10(3)/microm and enhance the electron mobility greatly (from tens to a few hundred of cm(2)/(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.