Functionalized vertical InAs nanowire arrays for gas sensing

Vertical InAs nanowires are contacted in situ using an air-bridge construction and functionalized with a metalloporphyrin (Hemin). The response of bare and functionalized vertical InAs nanowire arrays to ppb-level concentrations of NO2 and NO is demonstrated. Hemin enhances the response to NO whereas NO2 is also detected without functionalization. Transconductance measurements are used to investigate the effect of gas exposure on current density and electron mobility. Furthermore, the signal-to-noise ratio is shown to increase with the number of contacted nanowires, underlining the application of dense vertical nanowire arrays for sensing. Nanowire self-heating strongly enhances gas desorption, decreasing the recovery time.