CdS–CdTe Solar Cell Prepared by Vapor Phase Epitaxy

Abstract

CdS–CdTe solar cells were prepared by epitaxial growth of CdS on p·CdTe wafers, and properties of the cells were extensively studied. The cells have a junction structure of n·CdS–(n or i)·CdTe–p·CdTe. Formation of the (n or i) layer is due to diffusion of In into CdTe; the thickness of the layer was 0.5 µm in the most efficient cell. The best cell exhibited a solar conversion efficiency of 10.5% under illumination by sunlight (AM1.3, 68 mW/cm2), and 6.0% under illumination by a simulated sunlight (AMO). The high efficiency is attributed to the reduction in both the series resistance and surface recombination, which results from the presence of the heavily doped CdS layer on the wafer. The cell is not humidity sensitive and is stable in the forward bias test, These results suggest strongly that practically useful solar cells can be manufactured from this type of junction.