Characterization of metal contacts on and surfaces of cadmium zinc telluride

In the past several years significant progress has been made in building a database of physical properties for detector quality CdxZn1−xTe (CZT) (x=0.1–0.2) crystal material. CZTʹs high efficiency combined with its room temperature operation make the material an excellent choice for imaging and spectroscopy in the 10–200 keV energy range. For detector grade material, superior crystallinity and high bulk resistivity are required. The surface preparation during the detector fabrication plays a vital role in determining the contact characteristics and the surface leakage current, which are often the dominant factors influencing its performance. This paper presents a surface and contact characterization study aimed at establishing the effects of the surface preparation steps prior to contacting (polishing and chemical etching), the choice of the metal and contact deposition technique, and the surface oxidation process. A photoconductivity mapping technique is used for studying the effects of different surface treatments on the surface recombination.