Growth of CdZnTe crystal under high magnetic field and its photon-counting detector performance

Abstract

In this paper, CdZnTe (CZT) crystal was grown by the Traveling Heater Method (THM) under 5 T axial static magnetic field, which improved the quality of CZT crystal and the performance of photon-counting detector. The effect of high magnetic field on the quality of CZT crystal and the mechanism of internal defects were experimentally studied. The concentration of Te inclusions in CZT crystals grown by THM under high magnetic field was about 5 × 10³ /cm³ with the size less than 5μm observed by infrared microscope, which were one order of magnitude lower than those grown without magnetic field. Then the planar CZT detector was fabricated to study the photoelectric properties of CZT crystals grown by THM. The resistivity of CZT under high magnetic field was 2.83 × 10¹⁰Ω·cm, and its energy resolution to ²⁴¹Am (59.5 keV) was 5.9 %. The photocurrent maintained a good linearity under the tube current of 0.1mA-0.6 mA during the photocurrent response test. The results indicate that the detector prepared by CZT crystal grown under high magnetic field is better than that grown without magnetic field. Finally, the CZT wafers were made into 1 × 16 linear-array pixel detectors with a pixel size of 0.9 × 1.8 mm². The photon-counting rate and imaging quality of the CZT linear array detector under X-ray irradiation were studied. The average saturated photon-counting rate reached 2.0 × 10⁶ CPS/Channel (Counts Per Second/Channel).