Growth of highly c-axis oriented Mg:ZnO nanorods on Al2O3 substrate towards high-performance H2 sensing

Abstract

Highly c-axis oriented Mg:ZnO films were fabricated on Al2O3 substrate by radio frequency sputtering for different substrate temperatures. The crystal structure revealed that the Mg dopants are well integrated into ZnO wurtzite lattice. X-ray photoelectron spectroscopy measurements also confirmed the successful incorporation of Mg into ZnO. The substrate temperature exhibit significant influence on the optical absorbance and band gap of Mg:ZnO films. Scanning electron microscope images revealed the formation of Mg:ZnO nanorods with good crystalline quality. The films prepared at 1200 °C show well grown rods of Mg:ZnO due to strengthening of the preferred orientation of ZnO along the c-axis. The Mg:ZnO/Al2O3 films prepared at different temperature were tested for its sensing performance towards 200 ppm of H2 at room temperature. The Mg:ZnO sensor prepared at 1200 °C revealed fast response and recovery time of about 85 s and 70 s, respectively. The response of the sensor was linear to H2 concentration in the range of 100–500 ppm. It can be summarized that this high performance H2 sensor has potential for use as a portable room temperature gas sensor.