Schottky diodes based on electrodeposited ZnO nanorod arrays for humidity sensing at room temperature

A room temperature Ag/ZnO Schottky diode for relative humidity monitoring is presented. Electrodeposited ZnO nanorod arrays are used as sensing material. The response time is around 5 s and the sensitivity shows a logarithmic relation between 20% and 75% of RH. The electrical changes are observed to be related to the physical behavior of the Schottky diode according to the metal–semiconductor junction formed between the ZnO and the Ag. The sensing process is based on the adsorption of the water molecules on the nanorod surface and the reduction of the majority of carriers in the conduction band of the semiconductor, according to the relation associated to the work-function of Schottky barrier. A comparison on real time between the sensor developed and a commercial device corroborates the potential application of the new sensor presented in this work.