Modification of the Luminescence Properties of CZT Crystals Around Tellurium Inclusions

A 3D IR-mapping instrument has been recently developed at IMEM for the reconstruction of the position in three dimensions of Te inclusions inside CdZnTe crystals. Thanks to this apparatus, it has been possible to identify large Te inclusions ( ${>}20 \mu$ m) located just a few micrometers below the sample surface. Photoluminescence mapping of the region close to the inclusions revealed the enhancement of a near mid-gap band emission (0.78 eV) in correspondence with the defected region surrounding the inclusion. This supports the idea that the material surrounding Te inclusions presents a high concentration of deep levels probably acting as traps or recombination centers for carriers. The present result evidences the detrimental effect of Te inclusions on charge collection efficiency.