Performance optimization of transparent and conductive Zn1-xAlxO thin films for opto-electronic devices: An experimental & first-principles investigation

In the present work, a combination of the experimental techniques with first principle density functional theory (DFT) based calculations has been employed to study the performance of the aluminum doped ZnO (AZO) thin films as transparent conducting oxide (TCO) material. The AZO thin films with varying doping concentration (0 wt% to 10 wt%) and having thickness (<100 nm) were deposited on silicon substrate using pulsed laser deposition. Various structural, optical and electrical properties of the films have been explored using a variety of the experimental techniques e.g. X-ray diffraction, X-ray reflectivity, scanning electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy and current-voltage characteristic measurements. The different physical properties are observed following interesting trends where the characteristics property shows an optimum response at a particular doping concentration (5 wt%). These trends are correlated and explained based on the structural evolution in the nanostructured AZO thin films on varying doping concentration. Moreover, the prepared films are found to be having significantly high transmission and low resistivity making them useful for TCO application. The experimental findings for the Al-doped ZnO are supported by DFT calculations. Overall, our study provides important inputs to control the properties of Al doped ZnO films for their applications in optoelectronic devices.