Conduction mechanisms in SnO2 single-nanowire gas sensors: An impedance spectroscopy study

Results of studies on single and multiple SnO2 nanowire gas sensors with impedance spectroscopy are reported. Equivalent circuit modeling is used to draw fundamental conclusions about the dominant conduction mechanism in single-nanowire sensors, where the diameter of the nanowire is found to play a key role. This is then extended to multiple-nanowire sensors. For single-nanowire sensors, I-V measurements are also used to demonstrate that the contribution from the electrode-nanowire contact to the overall resistance changes with atmosphere and temperature. We find that for the randomly-orientated multiple-nanowire sensors, the main contribution to the resistance comes from the nanowire-nanowire junction.