Photoscanning of CdTe detectors for investigation of crystal quality and contact behaviour

N and P-type semi-insulating cadmium telluride crystals have been scanned with a 6 328 A laser beam performing a TV-type scan. The current response from the sample under test has been determined as a function of different parameters : nature of the contacts, electric field, polarity. It is demonstrated that information can be obtained on the type of conductivity of the material, its homogeneity, the field distribution and the transport properties of electrons and holes