PREPARATION AND FUNDAMENTAL PROPERTIES OF CDS CDTE HETEROJUNCTIONS

Devices of glass/SnO2/CdS/CdTe/Au were prepared. Polycrystalline CdS layers were deposited by spray pyrolysis whereas polycrystalline layers of CdTe were electroplated. Their structures were investigated by means of X-ray diffraction and well-crystalline phases were deduced from the results. Oscillations in the spectral dependence of the transmission indicated good optical quality and the thicknesses of the layers were computed from these curves. Measurement of dark I-U and C-U characteristics was used to study the charge transport in n-CdS-p-CdTe heterojunctions. The results can be explained by a model consisting of a series connection of a p-n junction and a voltage-independent resistance representing several intergranular barriers in the CdTe layer. Parameters of the junction such as the quality factor and the barrier height as well as the height and the number of intergranular barriers were determined. The ionized acceptor concentration in p-CdTe was established and its relationship to the deposition potential was found.