INTERPRETATION OF THE TEMPERATURE-DEPENDENT BEHAVIOR OF THE EMISSION FROM ISOELECTRONIC TELLURIUM CENTERS IN EPITAXIAL ZNSE1-XTEX

The emission from isoelectronic tellurium centres in metal-organic chemical vapour deposition ZnSe1-xTex has been investigated with photoluminescence and photoluminescence excitation spectroscopy. The emission is dominated by two bands, previously called the S1 and S2 bands and attributed to excitonic emission at isolated tellurium ions or tellurium ion pairs or clusters. We account for the temperature-dependent behaviour of these bands with a model in which the tellurium isoelectronic centres behave as spherical potential wells which trap holes via low lying resonant states in the valence band. Changes in intensity of the emission when both bands are observed together have been satisfactorily accounted for within the framework of this model and indicate that the Sl emission results from exciton recombination at tellurium pairs whilst the S2 emission results from recombination at tellurium triplets or larger clusters.