#research #radiation/detection-and-imaging/czt-detectors See also: [[@heReviewShockleyRamo2001]] # CdZnTe (CZT) Detectors Motivation: Just a basic page about CZT  (Picture of Kromek's CZT products) ## What are CZT Detectors? CZT detectors, or Cd$_{1-x}$Zn$_x$Te detectors are solid-state semiconductor radiation detectors. The material composition implies favorable properties for radiation detection, including a high Z, and bandgap energies of 1.64 eV which is useful for room temperature applications compared to [[High-Purity Germanium Detectors]] which must be cryogenically cooled. One important thing to note about CZT is that the [[Electron Mobility]] $\mu_e$ (1350 $cm^2/V\cdot s$) is a factor of ten great than that for holes $\mu_h$ (120 $cm^2/V \cdot s$) [^1]. This means that the electrons will be measured much more quickly than the holes, which can imply spatial characteristics based on how long it takes for the anode signal to be measured vs. the cathode signal. Per , The $\mu \tau_e$ ([[Mobility-Lifetime Product]] of electrons) of newer CZT crystals varies. Some sources say this value is around the order between $10^{-3} \, cm^2 / V$ [^3] and $10^{-2} \, cm^2 / V$ [^4], [^5]. [^1]: Knoll Radiation 4th Edition [^3]: [[@bolotnikovUseDrifttimeMethod2016]] [^4]: [[@buttacavoliIncompleteChargeCollection2022]] [^5]: [[@cho_measurement_2011]] Per He's lecture for MTV summer school, [[3D CdZnTe Gamma-Neutron Imaging Spectrometers]], the current energy resolution limit of CZT detectors is approaching 0.3% (presently it is 0.31% for single-pixel events as of [[@zhuPerformanceLargerVolume402021]]), but has decreased to that value from 1.7% in the last fifteen years. This initial issue was due to severe hole trapping, but was overcome through use of the [[Shockley-Ramo Theorem]] [^2] and a [[Frisch Grid]] initially, and has since improved with a pixelated-anode design. [^2]: Clair J. Sullivan's thesis, page 8 ## See also: - [[Current Imaging Modalities with CZT]] - [[Digital System (ASIC) Count Rate Capability in Counting Mode]] for Yuefeng's calculations of the Counting Rates of our current detector designs - [[Orion Group Pixelated CZT Schematics]]