Eddy current sensing of vertical Bridgman growth of Cd0.96Zn0.04Te

An encircling two coil eddy current sensor has been integrated into the ceramic liner of a commercial six zone vertical Bridgman furnace and used to monitor the growth of 72 mm diameter Cd0.96Zn0.04Te crystals. The sensor was maintained at a fixed location with respect to the ampoule and monitored melt cooling/composition, detected the position of the liquid-solid interface, measured the interface's curvature and determined the electrical resistivity of the solid during post-solidification cooling. The study confirmed earlier predictions that a two coil, multifrequency sensor approach can independently recover the liquid-solid interface location and provide insight about its curvature using data collected in the 50 kHz to 5 MHz frequency range. It suggests that the directional solidification of Cd0.96Zn0.04Te most probably initiates from a Cd-depleted melt, occurs in a colder than anticipated region of the furnace and progresses with a convex interface shape.