Conduction band minimum of CdTe

The spectral dependence of the photovoltaic effect for Au-n-type CdTe surface barrier cells is measured for photon energies near the CdTe intrinsic absorption edge at 298, 77, and 5°K. The results are viewed in terms of phonon assisted direct exciton absorption, phonon assisted exciton creation at a previously proposed lattice defect site, and indirect optical transitions. The data appears to favor the third mechanism although the second one is not ruled out as a possibility. The values for the direct transition energy gap obtained at the different temperatures compare favorably with those given by other work