Photoluminescence spectroscopy of CdTe epilayers grown by rf magnetron sputtering

Photoluminescence spectra are measured for sputter-deposited, heteroepitaxial (100)CdTe layers of thicknesses up to 14 μm grown on (100)KBr substrates. Three emission bands, at 0.81, 1.00, and 1.41 eV, are observed. From comparison of the photoluminescence spectra of the epilayers with those of several bulk single-crystal and polycrystalline samples, the origin of the 1.41-eV band, reported previously by many workers, is correlated to structural defects arising from lattice mismatch with the substrate. It is concluded that the 0.81- and 1.00-eV bands are due to defect levels resulting from nonstoichiometric growth. The injection level and temperature dependence of the photoluminescence suggest that the 1.41- and 0.81-eV emissions are donor-acceptor transitions whereas the 1.00- eV emission is a conduction-band-acceptor transition.