CdZnTe Detector Development

Cadmium Zinc Telluride (CdZnTe or CZT) semiconductor detectors are of great interest because they can provide high resolution X-ray and Gamma-Ray spectra at room temperatures. The CZT strip detectors under development at UNH will have performance capabilities and a packaging configuration applicable to a broad range of payload configurations. This includes balloon or spacecraft payloads and spans the photon energy range from 30 keV to at least 662 keV with excellent energy and position resolution. Performance over a wide field-of-view is enhanced by the capability to locate photon interactions in three dimensions within a thick, compact, large area image plane.
These detectors are well suited for fabrication of large area, high performance X-ray and g-ray imaging spectrometers. CZT detectors have the desirable properties of high stopping power, low thermal noise, room-temperature operation and, if carefully designed, excellent energy and spatial resolution and efficiency across a broad energy range. Our recent work has concentrated on developing a device based on an orthogonal coplanar anode strip design. This approach deals effectively with the problem of poor hole transport in CZT that severely limits the usefulness of traditional double-sided strip detectors. It achieves excellent energy resolution and offers the potential for using much thicker detector substrates. This, in turn, provides greater detection efficiency at higher energies (>500 keV), while maintaining the capability of sub-mm spatial resolution in three spatial dimen-sions. Furthermore, we have demonstrated a prototype packaging concept based on polymer flip-chip bonding, a breakthrough technology for CZT applications, that eliminates all wire bonds and permits the fabrication of large area imaging arrays with large packing fraction.

Our collaborators for CZT detector development are Dr. Valentin Jordanov at Yantra, Durham NH and Dr. Louis-Andre Hamel at the University of Montreal, Montreal, Canada.