Photoluminescence related to the interaction between carriers and structural defects in ZnTe crystals

High-quality bulk ZnTe single and polycrystals grown by the cold travelling heater method (CTHM) have been studied by photoluminescence (PL). Single crystals have been deformed in order to create structural defects and dislocations. The PL spectra of these deformed samples present the so-called Y-1 and Y-2 bands and an emission at 598-604 nm which has not been observed in nondeformed single crystals. This last band presents variations of the intensity as a function of the illumination time. The behaviour and analysis of the bands in the deep-level region indicate the existence of centres that likely produce a reduction in the carrier mobility. These centres can drastically degrade the properties of the material, hampering its use in optoelectronic devices or as a substrate for epitaxy.