Investigating the effect of Aluminum dopping on the structural, optical, electrical, and sensing properties of ZnO films

More recently aluminum doped zinc oxide (ZnO:Al) thin films have attracted a lot of attention as an alternative to indium tin oxide (ITO) for optoelectronic devices in order to produce energy such as solar cells. In this work, ZnO:Al thin films were deposited onto quartz and silicon substrates by RF magnetron sputtering technique and the effect of Al doping on structural, optical and sensing properties of the films were studied. The dopant concentration was varied between 1 wt.% and 3 wt.% in the thin films. The crystalline structure of the films were investigated by X-ray diffraction, which indicated wurtzite structure along (100) plane. The surface morphology of the films characterized by AFM revealed that the grain size decreased with increasing dopant concentration. The films also exhibited changes in optical properties due to a decrease in band gap with increasing Al concentration. Hall measurement confirmed that the ZnO films exhibited an n-type conductivity. The results of gas sensing experiments showed that the sensitivity of the ZnO films for detecting CO2 enhanced with an increase in dopant concentration