Advanced Vertical Electrodynamic Gradient Freeze System for High-yield CdZnTe Single Crystal Growth

The goal of the proposed project is to develop an innovative advanced Electrodynamic Vertical Gradient Freeze (VEDGF) crystal growth system with superior performance, versatility, stability, and longevity to produce large single-crystal CdZnTe wafers for long-wave infrared detector arrays. The project is aiming to develop an advanced VEDGF system that offers the following performance and capabilities: 1) Establishing a convex initial crystal growth interface to enable stable seeding from oriented single crystal seeds and suppress multi-grain nucleation in seedless crystal growth processes. 2) Maintain a convex shape throughout the crystal growth process. 3) Temperature control stability at the crystal-growth interface throughout the crystal-growth process. 4) Superior radial temperature uniformity. 5) Superior heater stability and longevity enabling stable, reproducible and uninterrupted growth-process performance for 12 months or more before system maintenance required. 6) Enabling the growth of 150-mm diameter (6”) CdZnTe boules. 7) Growth of CdZnTe crystal under tight Cd partial-pressure control from a separate Cd reservoir. 8) Modular heater design allowing efficient reconfiguration of heater zones and efficient and speedy heater servicing and repair. 9) Versatile temperature and motion control system design enabling the system to execute any of the following crystal growth processes: Vertical Gradient Freeze (VGF), VEDGF. Vertical Bridgeman (VB), and Traveling Heater Method (THM). To accomplish these goals the team will rely on advanced computational modeling of heat and mass transport in the growth crucible and heater assembly at the University of Minnesota and the practical experience of Nious Technologies using similar crystal growth systems incorporating many of the above design elements for the growth of seeded CdTe crystals. Approved for Public Release | 21-MDA-11013 (19 Nov 21)