Optimization of electrical and optical properties in multilayer TCO thin film structures

Multilayer oxide thin film stacks of aluminum doped zinc oxide (AZO) and tin doped indium oxide (ITO) have been sequentially deposited on soda lime glass substrates by RF sputtering of AZO and ITO ceramic targets at a substrate temperature of 150°C. The ratio of the AZO thickness to the ITO thickness is varied while keeping the total thickness of the stack constant. The electrical and optical properties of the multilayer stacks have been investigated as a function of this ratio and the number of interfaces. The experimental results are compared and their impact on device performance is demonstrated by simulations with validated AMPS-1D models. XRD and microscopy measurements have been carried out to understand the microstructure of the multilayer system and to establish its correlation with the opto- electric properties. The results have been evaluated for use of these multilayer TCO stacks as potential window layers for the photovoltaic solar cell applications.