Electrical Properties of Iodine-Doped CdTe Epitaxial Films on Si Substrates Grown by MOVPE

We studied the effect of iodine doping of CdTe films on Si substrates grown by MOVPE at different growth conditions. A high resistivity film was obtained by adjusting the growth temperature, Te/Cd precursor flow ratio and the dopant flow-rate. Our results show the film resistivity does not change linearly with the dopant flow-rate. The resistivity remains low and similar to that of undoped value for low dopant flow-rate, but increases abruptly when the dopant flow-rate is increased beyond certain value. Photoluminescence measurements of the films confirmed the dopant incorporation in the crystal. We explained the result of resistivity change due to the compensation of excess shallow acceptors by deep intrinsic donors.