The effects of UV radiation on the structure and properties of AZO thin films deposited on quartz glass by magnetron sputtering

Abstract

For many devices using AZO thin films as electrodes, such as thin film solar cells, the properties of AZO thin films have important influence on the life and performance of devices. The property stability of AZO thin films after long-term illumination is a problem that deserves attention. Two groups of ZnO:Al thin films were deposited on quartz glass substrates by magnetron sputtering at the same conditions. One group of the films was irradiated with ultraviolet (UV) light for 168h at room temperature and another group was just stored in the sample box at room temperature without irradiation. The structures and optical and electrical properties of the AZO films were investigated by XRD, FESEM, UV–Visible spectrophotometer and Four-point Probes. The results reveal that all the AZO films have hexagonal structure and highly preferred c-axis orientation. The mean grain size decreases and the diffraction angles move to larger angles after a long-time UV radiation. At the same time, the transmittance in visible region decreases and the sheet resistance increases. The optical bandgaps of AZO thin films are 3.28–3.38eV. The optical bandgap decreases a little bit after UV radiation. The transmittance of the AZO film deposited at higher pressure decreases more obviously.