Study of the effects of edge morphology on detector performance by leakage current and cathodoluminescence

© IEEE-Inst Electrical Electronics Engineers Inc. Manuscript received November 13, 2010; revised March 15, 2011 and May 09, 2011; accepted May 10, 2011. Date of publication June 27, 2011; date of current version August 17, 2011. This work was supported by the COCAE FP7 Project (http://www.cocae.eu).
The Vertical Gradient Freeze (VGF) method has been used to grow high resistivity Cadmium Zinc Telluride (CZT) for high energy radiation applications. In this work, the effect of lapping and polishing the lateral edges of planar detectors is studied. Expectations that improved surface morphology of the edges should correlate with reduced surface leakage current are shown to be erroneous. The effect of various types of lateral edge treatments on detector performance was observed before and after each surface modification. Complementary results were obtained using I-V, Cathodoluminescence (CL), and gamma ray response measurements using 133Ba. As a result, a quick and easy method is reported which minimizes leakage current and actually enhances detector performance through the introduction of surface defects. It is demonstrated that the introduction of radiative recombination centers helps reduce surface leakage current in the detector by a factor of up to 200%, depending on the surface treatment. The purpose of this work is to identify material processing steps for fabricating planar devices based on CZT for gamma ray spectroscopy.
Depto. de Física de Materiales
Fac. de Ciencias Físicas
TRUE
pub