Structural study and sensitivity measurements of ZnO based ammonia (NH3) sensor

Zinc Oxide (ZnO) thin films were prepared on thermally oxidized SiO₂ by radio frequency (RF) magnetron sputtering at various substrate temperature ranging from room temperature (25°C) to 500°C. The surface morphology and crystallinity were analyzed by field emission scanning electron microscopy (FESEM) and X-Ray Diffractometer (XRD) respectively. The grain size measured by FESEM is increasing with the increased of substrate temperature used. All films grown were c-axis oriented and the film deposited at 300°C exhibit the highest crystallinity. The film deposited at room temperature exhibit the highest sensitivity due the smallest grain size and the highest surface to volume ratio.