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 c rystals have been deformed in order to create structural defects and disloc ations. 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 inte nsity 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 drast ically degrade the properties of the material, hampering its use in optoele ctronic devices or as a substrate for epitaxy.