Influence of the Zn plasma kinetics on the structural and optical properties of ZnO thin films grown by PLD

We analyze the effect of the average kinetic energy of Zn ions on the crystalline orientation and quality, along with its effect on the optical response of ZnO thin films deposited by reactive pulsed laser deposition. With the use of laser attenuators, the Zn plasma density was kept constant while the mean kinetic ion energy was varied from 40 to 100 eV. The results show that the films are polycrystalline with a preferential orientation along the [101] direction. As the mean kinetic energy of the ions in the plasma is increased, the degree of crystallinity decreased. The preferred orientation was found to be a plasma-related effect. As deposited films show high transmittance in the visible range and an intense UV photoluminescence emission, which is associated to the excitonic recombination.