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

In this work, aluminium doped zinc oxide (ZnO: Al) thin films were deposited onto quartz and silicon substrates by RF magnetron sputtering technique and studying the effect of Al doping on structural, optical and sensing properties of the films. The dopant concentration was varied from 1 to 3 wt.% in the ZnO 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 characterised 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 gas enhanced with an increase in dopant concentration.