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Characterization of Extended Defects Observed in Cadmium Zinc Telluride (CZT) Crystal

Published online by Cambridge University Press:  28 May 2015

Samuel Uba ,
Stephen Babalola ,
Anwar Hossain  and
Ralph James
Samuel Uba
Affiliation:
Alabama A&M University, Normal, AL 35811, U.S.A
Stephen Babalola
Affiliation:
Alabama A&M University, Normal, AL 35811, U.S.A
Anwar Hossain
Affiliation:
Nonproliferation and national security, Brookhaven National Laboratory, Upton, NY 11973, U.S.A
Ralph James
Affiliation:
Nonproliferation and national security, Brookhaven National Laboratory, Upton, NY 11973, U.S.A
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Abstract

Cadmium Zinc Telluride (CZT) semiconductor crystal properties have been studied extensively with a focus on correlations to their radiation detector performance. The need for defect-free CZT crystal is imperative for optimal detector performance. Extended defects like Tellurium (Te) inclusions, twins, sub-grain boundaries, and dislocations are common defects found in CZT crystals; they alter the electrical properties and, therefore, the crystal's response to high energy radiation. In this research we studied the extended defects in CZT crystals from two separate ingots grown using the low-pressure Bridgman technique. We fabricated several detectors cut from wafers of two separate ingots by dicing, lapping, polishing, etching and applying gold metal contacts on the main surfaces of the crystals. Using infrared (IR) transmission microscope we analyzed the defects observed in the CZT detectors, showing three dimensional scans and plot size distributions of Te inclusions, twins and sub-grain boundaries observed in particular regions of the CZT detectors. We characterized electrical properties of the detectors by measuring bulk resistivity and detector response to gamma radiation. We observed that CZT detectors with more extended defects showed poor opto-electrical properties compared to detectors with fewer defects.

Keywords

crystaldefectsgrain boundaries
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1792: Symposium CC/FF – Defects and Materials Issues in Semiconductors―Relationship to Optoelectronic Properties and Device Reliability , 2015 , mrss15-2134263
Copyright
Copyright © Materials Research Society 2015 

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References

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