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.^[1]

Characteristics

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

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.^[2] CZT can be formed into different shapes for different radiation-detecting applications, and a variety of electrode geometries, such as coplanar grids ^[3] and small pixel detectors,^[4] 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.^[5] Pixelated CZT with a volume of 6 cm³ can achieve 0.71% FWHM energy resolution at 662 keV and perform Compton imaging.^[6]

See also

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