Identification of edge and exciton emission centres in CdTe

Examination of the edge and exciton luminescence emitted by cadmium telluride before and after monoenergetic electron irradiation (in the 100-400 keV range) coupled with previous results of work on heat treatments in cadmium vapour and tellurium vapour has shown the necessity for considering the existence of not only singly charged defect states but also doubly charged defect states in this material. This permits the explanation, in the case of cadmium telluride, of the weakness or nonexistence of phonon replicas and also the great sensitivity to electron damage shown by certain of the exciton lines. The 1.587 eV emission is attributed to an exciton bound to a neutral double acceptor centre believed to involve the cadmium vacancy. Transition of an electron from the conduction band to the ground state of the same neutral acceptor produces the 1.572 eV emission.