A New TCO/window-buffer Front Stack for CdTe Solar Cells and its Implementation

A new TCO/window-buffer combination is presented for use in thin film CdTe solar cells. The TCO layer is cadmium tin oxide (CTO) and the window-buffer layer is tin magnesium oxide (TMO). Zinc magnesium oxide (ZMO), previously utilized by other groups and our group, was also prepared. The layers were produced by hollow cathode sputtering and were characterized by optical and Hall effect measurements. It was found that the carrier concentration of the window (buffer) layer at a fixed Mg concentration could be controlled over a wide range. CdTe solar cells were fabricated on glass/TCO/TMO and other bilayers without use of CdS. Quantum efficiency data confirmed the greatly improved blue response of the cells.