No abstract

The formation of ternary CdSxTe1–x alloys during CdTe solar cell production is quantitatively investigated using optical and quantum efficiency measurements. Both the diffusion of sulphur into the CdTe and of tellurium into the CdS film are analysed in the context of film thicknesses and the activation step used in CdTe solar cell processing. We present a method of determining the tellurium content in the CdS layer from EQE measurements. The tellurium content is limited to small values and depends on the CdS thickness. A CdSxTe1–x phase of several 100 nm thickness is generated in the CdTe film during the activation step. This phase changes the optical bandgap in the depletion region and gains importance in cells with thin absorbers. The comparison of solar cells with and without CdS layer illustrates the crucial role of the CdS buffer layer for the p‐n junction. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)