Optimization of oxide-semiconductor/base-semiconductor solar cells

In order to get the maximum output from oxide-semiconductor/base-semiconductor solar cell, one has to incorporate an ultrathin insulating layer so that the resulting configuration is a semiconductor-insulator-semiconductor (SIS) diode. The performance of such SIS diodes is equivalent to a metal-insulator-semiconductor (MIS) solar cell. The key parameters in the optimization are the thickness of the insulating layer and the work function of the oxide semiconductor. Using the existing knowledge of the parameters for a number of oxide semiconductors one would conclude that ITO, ZnO, and SnO2are good oxides for the fabrication of SIS solar cells. Some properties of highly conducting and highly transparent ZnO films which have been fabricated in our laboratory are presented. These results suggest that these ZnO films should be useful for fabricating low-cost SIS solar cells.