Theoretical and experimental studies of Al-doped ZnO thin films: optical and structural properties

This study presents the results of theoretical and experimental investigations of zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films, prepared by RF magnetron sputtering. The structural, optical and morphological properties were examined, and the results show that the AZO thin films exhibit a higher optical transmittance compared to intrinsic ZnO films of the same thickness. Also, the XRD data show a change from vertical growth along (002) crystallographic plane to lateral growth along (103) crystallographic plane with Al doping. The experimental optical parameters of the prepared ZnO and AZO films were determined and confirmed by the density functional theory (DFT), while the corresponding electronic structures have been investigated using DFT calculations with modified Becke–Johnson exchange potential (mBJ) and generalized gradient approximation (GGA). From the results, it is shown that the optical band gap is blueshifting from 3.13 eV to 3.45 eV with Al doping due to the Burstein–Moss effect.