EFFECT OF DEGRADATION ON THE QUALITY AND PERFORMANCE OF ALUMINIUM-DOPED ZINC OXIDE (ZNO) THIN FILMS DEPOSITED ON FLAT GLASS

Four Aluminium doped zinc oxide (ZnO:Al) thin-film layers on three flat glasses and a nanostructured substrate were subjected to long term degradation conditions for two years. The thin films were stored under normal laboratory conditions in a plastic bag to induce slight heat damping at times to accelerate the physical and chemical degradation process. Low temperature fabricated transparent conductive oxide (TCO) aluminium doped Zinc oxide (AZO) has attracted much interest in solar cell application due to its opto-electrical properties. However, its application is limited because of instability to temperature, fast degradation, and low reliability in the presence of an acidic medium. These parameters (temperature, degradation and acidic medium) can be used as a gauge for assessing the stability of TCO devices. Various AZOs of different doping material were used to demonstrate how degradation influences the roughness of AZO thin film. The long-term effect of the doping substance in mitigating the effect of AZO degradation was investigated in this work, by exploiting the interplay between surface morphology and defects. The roughness/degradation of the different thin films was evaluated using scanning probe microscopy (SPM) to demonstrate degradation. The roughness analysis was compared to the initial roughness after fabrication of the thin films. The analysis showed that different dope substances offer different mitigation levels, and that AZO/Car had less morphological degradation. Studies by scanning probe microscope showed that surface roughness and structural changes were due to the degradation of AZO films, and the low RMS roughness of AZO:Al/Car after degradation reflected the stability degradation of AZO films in an underwater electrolysis environment . The low RMS roughness of AZO:Al/Car reflected the higher stability of this thin film evident from the low degradation of AZO:Al/Car thin film.