PHOTOLUMINESCENCE STUDY OF CADMIUM TELLURIDE GROWN BY THE BRIDGMAN TECHNIQUE

Temperature and excitation power dependence photoluminescence (PL) spe ctroscopy was performed on bulk CdTe samples grown by the Bridgeman te chnique at liquid helium temperature, Bright edge-emissions are observ ed from all samples. Thermal quenching behavior of the amplitude of em ission peaks at 1.538 eV and 1.49 eV is described with activation ener gies of epsilon 1 = 10 meV, epsilon(2) = 5 meV and epsilon(1) = 14 meV , epsilon(2) = 5 meV, respectively. These activation energies give evi dence that donor states are related to 1.538 eV and 1.49 eV emissions. The PL amplitude dependence on the excitation power at liquid helium temperatures are described by the values of nu = 1.6 and 0.91, respect ively. With the results of PL intensity dependence on temperature and excitation power density, the emission peak at 1.538 eV is identified as the DAP recombination involving shallow donors and the substitution al sodium and/or lithium acceptor and the 1.49 eV emission peak as the DAP recombination related to shallow donor states and the substitutio nal silver acceptor.