Precise laser-induced local modification of AZO:Ag films and their optical properties

•Continuous wave laser radiation is promising for local annealing of ZnO:Al thin films with metal nanoparticles.•After laser influence the band gap was increased and the plasmon resonance peak was shifted.•A photothermal mechanism was proposed to explain the laser-induced film modifications. The paper presents precise modifications of ZnO:Al thin films with silver nanoparticles by CW laser leading to the improvement of the composite structure and optical properties. The violet laser wavelength (405 nm) was chosen to be far from the plasmon resonance wavelength. The morphology of the obtained ZnO:Al thin films with silver nanoparticles was investigated. It was detected that under an exposure by laser power densities I0 = 0.89 MW/cm2 and I0 = 1.07 MW/cm2 and scanning velocities Vsc = 100 μm/s and Vsc = 50 μm/s, the film structure became denser, the size of ZnO:Al crystallites increased, and the size of silver nanoparticles decreased. The effects of laser radiation on the optical characteristics of the samples were then investigated. Particularly, a blue shift of the plasmon resonance peak and an increase in the bandgap from 3.27 eV to 3.36 eV were obtained. Additionally, numerical modeling was performed based on a photothermal film processing mechanism and clearly explained the observed effects.