Study on the response of InAs nanowire transistors to H2O and NO2

Through studying the transfer curve of field effect transistors (FETs) and the current response at various gate voltages, we observe that the adsorption of H2O vapor and NO2 introduce opposite effect to the performance of InAs nanowire (NW) FETs compared with that in the vacuum. Although the hysteresis in the transfer curve increases in both the gases, the threshold voltage shifts negatively in H2O vapor and positively in NO2/N2 gas due to the different response mechanisms. The transconductance and the field-effect mobility of the devices do not change in H2O for both the gate voltage sweeping directions and in NO2/N2 for forward sweeping compared with that in the vacuum, probably due to the InOx layer covering the InAs NW. Importantly, current response to H2O and NO2 can be modulated by the gate voltage. Analysis suggests that the effect of H2O adsorption is to increase electron density, while the effect of NO2 adsorption is to decrease the electron density in the channel.