Cadmium zinc telluride

Cadmium zinc telluride, (CdZnTe) or CZT, is a compound of cadmium, zinc and tellurium or, more strictly speaking, an alloy of cadmium telluride and zinc telluride. A direct bandgap semiconductor, it is used in a variety of applications, including semiconductor radiation detectors, photorefractive gratings, electro-optic modulators, solar cells, and terahertz generation and detection. The band gap varies from approximately 1.4 to 2.2 eV, depending on composition.

Characteristics

File:YanDavos on SPOT.jpg

A YanDavos radiation sensor system based on a 1 cm³ CZT crystal, deployed on a Boston Dynamics Spot quadruped robot for radiation mapping in the Chernobyl Exclusion Zone

File:Cs137Spectra.tif

A Cs-137 gamma-ray spectrum collected using an M400 pixelated CZT imaging spectrometer. Energy resolution, as measured by full-width-at-half-maximum (FWHM), is better than 1%.

Radiation detectors using CZT can operate in direct-conversion (or photoconductive) mode at room temperature, unlike some other materials (particularly germanium) which require cooling. Their relative advantages include high sensitivity for X-rays and gamma rays, due to the high atomic numbers of Cd and Te, and better energy resolution than scintillator detectors. CZT can be formed into different shapes for different radiation-detecting applications, and a variety of electrode geometries, such as coplanar grids and small pixel detectors, have been developed to provide unipolar (electron-only) operation, thereby improving energy resolution. A 1 cm³ CZT crystal has a sensitivity range of 30 keV to 3 MeV with a 2.5% FWHM energy resolution at 662 keV. Pixelated CZT with a volume of 6 cm³ can achieve 0.71% FWHM energy resolution at 662 keV and perform Compton imaging.

See also

• Scintillator
• cadmium telluride
• zinc telluride
• Telluride (chemistry)

External links

• National Pollutant Inventory - Cadmium and compounds