Infrared LED Enhanced Spectroscopic CdZnTe Detector Working under High Fluxes of X-rays

Abstract

This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe detector. CdZnTe detectors operating under high radiation fluxes usually suffer from the polarization effect, which occurs due to a screening of the internal electric field by a positive space charge caused by photogenerated holes trapped at a deep level. Polarization results in the degradation of detector charge collection efficiency. We studied the spectroscopic behavior of CdZnTe under various X-ray fluxes ranging between 5×105 and 8×106 photons per mm2 per second. It was observed that polarization occurs at an X-ray flux higher than 3×106 mm−2·s−1. Using simultaneous illumination of the detector by a de-polarizing LED at 1200 nm, it was possible to recover X-ray spectra originally deformed by the polarization effect.

Effect of Deep-Level Defects on the Performance of CdZnTe Photon Counting Detectors

“…These large-volume, good-uniformity CdZnTe photon counting detectors, which can detect a photon flux in the order of a hundred million mm −2 s −1 , are necessary for many applications such as medical and industrial imaging [8,9]. Although such high-flux CdZnTe detectors have been reported [10], it is still a challenge to achieve large-scale commercial applications, primarily due to the material defects which can lead to the polarization effect [11][12][13][14][15][16]. Under high X-ray flux conditions, excessive positive space charges formed by trapped holes build up inside the detector, which have an opposite effect on the externally applied voltage and ultimately result in a non-uniform electric field and catastrophic device failure.…”

Application of CdZnTe Quasi-Hemispherical Detectors in Strong Gamma-Radiation Fields

“…Such complex behavior of leakage currents and energy resolution under the influence of high gamma-radiation fluxes and IR illumination can be associated with a change in an electric field distribution in the detector caused by formation of a space charge due to trapping of photo generated holes at deep levels and their detrapping under the influence of IR illumination [9]. A detailed explanation of the effects found requires additional research.…”

Mapping of inhomogeneous quasi-3D electrostatic field in electro-optic materials

“…Our recent reports show various applications of 1D electric field evaluation method related to the space-charge distribution and presence of deep defect levels in planar CdZnTe and CdZnTeSe detectors 20 , 21 . The effects of a high flux of incident X-rays, commonly used in medical applications, were also investigated 22 . Another application exploits the relatively high thermal neutron capture cross-section of isotope in CdZnTe with the neutron reaction followed by effects accompanied with the creation of clouds of ionization charge.…”