The Effect of Low-Temperature Annealing on a CdZnTe Detector

It is known that low temperature annealing at below 200 degrees C decreases the leakage current in a CdTe and CdZnTe (CZT) detector. However, only CZT detectors which have electrodes made by electroless method and low temperature annealing in the air showed diminished leakage current after annealing. With the aid of an in-situ annealing monitoring system, we measured the leakage current of a CZT detector while carrying out low-temperature annealing. A decrease in the leakage current resulted from the presence of thin insulating Te oxide layers, TeO2 and CdTeO3, instead of CZT/electrode interface enhancement by diffusion of Au. Other measurement results of Auger electron spectroscopy, micro TEM analysis, and pulse height spectrum were in good agreement with our new interpretation of the low temperature annealing effects of CZT.