Study on Solute Transport and Crystal Growth of Cdznte by Traveling Heater Method Under Axial High-Intensity Static Magnetic Field

Abstract

Nowadays, the CdZnTe nuclear detector is the hotspots in fields of photon-counting nuclear medical imaging and environmental monitoring. The Traveling Heater Method (THM) is demonstrated to be a promising way to grow high-quality detector-grade CdZnTe crystals. However, the low growth velocity (3-5 mm/day) during the THM growth of CdZnTe hinders its commercial applications. In this work, six sets of solute transport experiments and four groups of crystal growth experiments were conducted to investigate the influence of high-intensity static magnetic field (SMF) on solute transport characteristics in the Te solution region and crystal growth during the THM growth of CdZnTe crystals. It’s found that the solute transport velocity in both the CdZnTe polycrystals above and below pure Te solvent increases from 30.28 mm/h to 32.54 mm/h and from 0.28 mm/h to 1.17 mm/h, respectively. Since the introduction of a SMF induces thermoelectric magnetic convection (TEMC) near the solid-liquid interface, which enhances the transportation of CdZnTe in Te solutions. During THM growth of CdZnTe crystal, in the absence of SMF, the growth interface turned from concave at the growth velocity of 0.3 mm/h to a growth interfacial region with the growth velocity increased to 0.9 mm/h. In the presence of 5 T SMF, the growth interface turned from the convex at 0.3 mm/h to the wave-like at 0.9 mm/h. The convex interface at 5 T SMF facilitates single-crystalline growth, which resulted large-grains in the center and no voids within the crystal. Therefore, under a growth velocity of 0.3 mm/h and a 5 T SMF, CdZnTe crystal with high single-crystal yield, uniform distribution of Te inclusions (size of 3-10 μm with a concentration of 1.21 ×104 cm), and an energy resolution of 6.8% under the 241Am irradiation were obtained by THM.

Keywords: Traveling Heater Method, CdZnTe, Solute transport, static magnetic field