Application of eddy current technique to vertical Bridgman growth of CdZnTe

The eddy current technique was used to reveal the interface shape during vertical Bridgman growth of CdZnTe and to follow changes in the properties of the solidified ingot as it was cooled to room temperature after growth. Experiments were performed where partially solidified charges were decanted to show the interface shape. Eddy current analysis of the partially solidified charge indicated a concave interface shape in qualitative agreement with the shape of the decanted ingot. However, due to noise, interference, and possibly the inhomogeneous nature of the melt, only some of the eddy current signals could be analyzed empirically for interface shape; absolute values of conductivity could not be calculated from the eddy current data. Eddy current measurements made to follow changes in conductivity during post-growth cooling showed a minimum in the data during an 800 degrees C annealing step indicative of a transition in the electrical properties of the ingot. On further cooling, a dramatic increase in the bulk conductivity of the ingot was noted. Such a transition can probably be described as a Mott transition.