Capacitive humidity sensors based on zinc oxide nanorods grown on silicon nanowires arrays at room temperature

Silicon nanowires (SiNWs) with a length of about 8 mu m and zinc oxide nanorods (ZnONRs) with a length of about 200 nm were prepared by wet chemical etching and chemical bath deposition, respectively. Capacitive humidity sensors based on ZnONRs/SiNWs were fabricated and their humidity sensing properties were examined at room temperature (similar to 25 degrees C). The largest response range of the sensors is 2.40-64.40 nF when the relative humidity (RH) changes from 11.30 to 97.69%. The sensitivity is 0.69 nF/% RH. The longest response and recovery time is similar to 26 and 7s, respectively, which corresponding to 97.69% RH. The sensors are proven to have long-term stability, with a maximum relative standard deviation (RED) of 2.93% corresponding to 11.30% RH during about one month at room temperature in air. ZnONRs/SiNWs are a better ideal capacitive humidity sensing material compared to those we previously reported. It might be easy to miniaturize and compatible with traditional integrated circuit (IC) process. (C) 2015 Elsevier B.V. All rights reserved.