Two-dimensional photocurrent mapping of mercuric iodide detector crystals

We have employed two-dimensional photocurrent mapping to determine the material uniformity of a 1 cm3 cube of mercuric iodide configured as a detector. The sample was mapped over the cross-sectional face of the crystal between the two Pd contacts used to bias the sample. We have examined the dependence of the photocurrent response on detector bias, and also observed non-uniformities within the detector area. A model predicting the photocurrent as a function of position between the contacts has been related to the experimental results and is also presented. (orig.)