Spectroscopic Response of CZT Detectors Obtained by the Boron Oxide Encapsulated Vertical Bridgman Method

Great efforts are being presently devoted to the development of CdTe and CdZnTe detectors for a large variety of applications, such as the basic, medical, industrial, and space research. The purpose of this work is to present the spectroscopic proper ties of some CZT crystals grown by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR. By this technique the crystal, during the growth, is fully encapsulated by a thin layer of liquid boron oxide, so that the crystal-crucible contact is prevented, thus allowing larger single grains with lower dislocation density to be obtained. Several detectors were realized about 4 mm x 4 mm x 1 mm in size, with two planar gold contacts on both the surfaces realized by an electroless technique. The behavior of these detectors was studied as a function of the bias voltage, irradiation geometry and energy of the interacting photons. Good electron charge collection properties have been demonstrated and electric field distribution has been investigated using the Pockels effect.