Dielectrophoresis-Assembled ZnO Nanowire Oxygen Sensors

Zinc oxide (ZnO) nanowire (NW) devices are fabricated on photolithographically patterned microelectrodes by a scalable dielectrophoresis process using synthesized NW inks. Current-voltage characteristics measured under different pressures of argon, nitrogen, and air identify the chemical adsorption and desorption of oxygen species as the main mechanism underlying the changes in conductance, as opposed to piezoelectric effects. The sensitivity of the ZnO NW oxygen sensor is critically dependent on temperature, annealing, and ohmic or Schottky nature of the contacts.