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2005
Journal Article
Titel
Optimized TCO deposition and etching for a-Si:H thin film solar cells
Abstract
Throughout recent years, strong efforts have been made to develop Al-doped ZnO films on glass as a transparent and conductive front electrode for amorphous or amorphous/microcrystalline thin films silicon solar cells. Compared to the well known SnO2:F films deposited by CVD, ZnO:Al technology allows for better performance at low cost especially because ZnO:Al can be textured in order to enhance the light scattering into the cell. As a milestone towards industrial scale ZnO:Al production, an optimized process for the reactive sputtering of ZnO:Al has been developed at Fraunhofer IST. This robust process allows for initial cell efficiencies of more than nine per cent for single junction amorphous silicon solar cells on commercial soda lime float glass substrates. The crucial point for achieving these high efficiencies is to optimize the surface morphology after the wet etching roughening step due to the control of deposition parameters such as oxygen partial pressure, Al-content of the targets and substrate temperature.