RF magnetron sputtering is used to deposit Aluminum-doped zinc oxide (ZnO:Al) films on glass and p-Si substrates. This work is a study of ZnO:Al films grown at different RF powers for photovoltaic cells application, as antireflective (AR) coatings. At room temperature and argon gas pressure of 0.6 Pa, RF power was changed from 200 to 400 W. The structural, electrical and optical properties of ZnO:Al films were investigated. Under theses conditions, we have obtained c axis-oriented wurtzite structure ZnO thin films with high transmission (>85%) and low reflection in visible wavelength range and a band gap of 3.34 eV. The results of this study suggest that the variation of the RF power, used for growth, allows the control of the structural and optical properties of the films. ZnO:Al films can be used in optical applications as thin films antireflective coatings.