Material study on reactively sputtered zinc oxide for thin film silicon solar cells

Aluminum doped zinc oxide (ZnO:Al, AZO) films were prepared by reactive mid frequency magnetron sputtering. We characterized the electrical and optical properties as well as the surface morphology obtained after wet chemical etching. The carrier mobility could be increased up to 42 cm2/Vs and the transmission between 400 and 1100 nm was enhanced by the reduction of aluminum content in the targets. The working point of the reactive sputtering process strongly influences the etching behavior and was used to optimize the light scattering properties of the ZnO:Al films after wet chemical etching. Finally, the texture-etched ZnO:Al films were successfully applied as substrates for silicon thin film solar cells.