EFFECT OF DOPANTS ON THE CONDUCTIVITY OF ELECTRODEPOSITED CDTE

Thin-film polycrystalline CdTe was electrodeposited as described previously onto indium-tin-oxide coated glass under argon and then stored either under argon or air before and after the annealing step. Dopants were incorporated into films by several methods. Indium, Cadmium, and silver were introduced into the films either by codeposition or by electromigration techniques as described previously for copper, and the doping process was followed by heat treatment. Tellurium was introduced into two films by heating the samples in a tellurium atmosphere, and the effect of oxygen on the CdTe was investigated by a high-temperature heat treatment in air. The effect of these doping procedures on the conductivity was investigated at various temperatures. For this purpose, a system was built to measure extremely high resistances (>101 2) over a large and well-controlled temperature range. Because of the polycrystalline nature of the films, the results are discussed in terms of a model in which the conducitivity is affected by the density of grain boundary states.