Two-step thermal process in tellurium vapor for tellurium inclusion annealing in high resistivity CdZnTe crystals

Abstract

Exploitation of CdZnTe crystals for X-ray imaging detectors is limited by the incorporation of tellurium inclusions during growth. Over the years, several post-growth thermal treatments have been proposed for the removal of tellurium inclusions, often compromising the high electrical resistivity of the material. Moreover, main attention is usually paid to large inclusions, whose direct connection with the deterioration of detector properties has been demonstrated, while the effect of thermal annealing on small inclusions is usually neglected.In this article, the effect of different thermal annealing process on the concentration of inclusions down to 1μm size is studied. A two-step process in tellurium vapors has been shown to be effective to anneal large tellurium inclusions and to preserve the high resistivity of the samples as well.