ZnO-nanorod-based resistor-type ammonia gas sensors with underlying Pt/Cr interdigitated electrodes have been fabricated and investigated. The response is improved by reducing the electrode spacing d. Experimentally, a high response of 80.6 is found when d is reduced to 2 μm under exposure to a 1000-ppm NH 3 /air gas at 300 °C. A lower detection limit of 10-ppm NH 3/air at 300 °C is also obtained. This device possesses response and recovery times of $<$ 3 min even at low ammonia concentrations (10 ppm). The enhanced ammonia-sensing capability with reducing electrode spacing d could be attributed to the formation of more ZnO grain boundaries. A simple cross-linked structure model is presented to interpret the ammonia-gas-sensing performance, and a good correlation between theory and experiment is demonstrated.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering