Eddy current sensor concepts for interface characterization during Bridgman growth of CdZnTe single crystals
Hg1−xCdxTe Infrared (IR) focal plane arrays are today manufactured on IR transparent CdTe or (lattice matched) Cd1−yZnyTe substrates obtained from single crystals grown by a Bridgman method using furnaces with a temperature gradient[1–4]. The yield of single crystal substrate material produced by this method is poor, in part because of the absence of sensor techniques to characterize (and allow control of) the liquid-solid interface shape during crystal growth. This interface, which represents the melting point isotherm of the system, may be convex, ideally flat, or concave. It is determined by heat flow near the interface which is governed, in part, by where solidification occurs in the furnace.