The effects of chemical etching on the charge collection efficiency of {111} oriented Cd0.9Zn0.1Te nuclear radiation detectors

We report the effects of different etchants on the mobility-lifetime product (μτ) of cadmium zinc telluride (CZT). The μτ values were obtained via the Hecht relation. The effects of surface recombination were also investigated using photoconductivity measurements. Results were obtained for a {111} oriented CZT single crystal. We find that the surfaces behave differently after etching. Values for surface recombination rates for [111]A and [111]B surfaces can vary by up to two orders of magnitudes for the same etchant. This large variation in surface recombination rates affects the charge collection efficiency and detector performance. We report surface treatments that enhance the charge collection efficiency for [111]A and [111]B surfaces. Data describing the detector response for Am²⁴¹ spectra current-voltage relationship, and bulk μτ values and surface recombination rates are shown for different etchants.