THERMOMIGRATION OF TELLURIUM PRECIPITATES IN CDZNTE CRYSTALS GROWN BY VERTICAL BRIDGMAN METHOD

Te precipitates in CdZnTe have been characterized by x-ray diffraction at room and higher temperatures. From the x-ray results at room temperature, it has been confirmed that Te precipitates in CdZnTe have the same structural phase as observed in elemental Te under high pressure. The x-ray results at higher temperature indicate that Te precipitates melt around 440 degrees C. CdZnTe samples containing Te precipitates have been annealed at temperatures below and above 440 degrees C with thermal gradient of similar to 70 degrees C/cm. Results of the observation with infrared microscope before and after the annealings indicate distinct occurrence of thermomigration of Te precipitates in samples annealed at temperature above 440 degrees C compared with ones annealed at temperature below 440 degrees C. Thermomigration velocity obtained from these results is similar to 50 mu m/h. The average value for the effective diffusion coefficient of the metallic atoms in Te precipitates calculated by using the thermomigration velocity is similar to 3 x 10(-5) cm(2)/s.