Analysis of flat glass deposited thin film made from aluminium doped zinc oxide (AZO)

Abstract

Doped aluminium zinc oxide (Al doped ZnO/AZO) thin films that were synthesised on glass and nanostructured with cadmium substrates were allowed to degrade over a period of two years in a controlled environment. The films were placed in airtight containers for eighteen months and later placed in plastic containers for four months at room temperature. This environment was able to allow slight damping at times to accelerate the physical degradation process. The evolution of transparent conductive oxide (TCO) like aluminium doped zinc oxide (AZO) has been a welcome development in solar cell production. But it quickly deteriorates which is a drawback in its application. In this study, each film was doped with the same Al concentration but in different mediums such as cadmium, nitrogen, silver and argon (Cd, N2, Ag, Ar). To investigate the optical performance, the transmittance of each film was studied. An average transmittance of above 65 % was observed. The optical properties in these films were varied by the different mediums which are cadmium, nitrogen, silver and argon (Cd, N2, Ag, Ar). It was observed that the transmission over the visible range varied as the wavelength increased. This change happens because of free carriers coupling to the electric field leading to high reflection. Therefore, the simplest way to quantify the degree of degradation was to investigate the optical properties such as the transmission between layers. The micro-structure of these thin films were evaluated using scanning probe microscopy (SPM) to demonstrate degradation. Finally, the morphological and elemental compositions were analysed with scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy (EDX).