CdZnTe detectors for gamma spectroscopy and x-ray photon counting at 250 × 106 photons/(mm2 s)

Abstract

Using the traveling heater method, we have developed commercial CdZnTe (CZT) crystal growth, fabrication, and in-house test technologies for both, photon-starved gamma spectroscopic sensors and high-flux x-ray photon-counting for medical imaging and other applications. We compare the performance of different CZT material types for gamma spectroscopy and for high-flux x-ray imaging. We demonstrate single-threshold photon counting and basic imaging capability of pixelated CZT detectors at the highest x-ray fluxes we could generate in-house, i.e., ∼250 × 106 photons/(mm2 s). We show that the test system can be used for universal, absolute flux calibration of x-ray beams based on an accurate pile-up fitting algorithm. The detectors also perform spectroscopically under high-flux, when tested with energy discriminating electronics. A brief investigation on the effects of leakage, photo, and excess currents including their temporal behavior is also presented. Sub 1% uncorrected single-pixel resolution of the 662 keV 137Cs full energy peak was achieved with the gamma spectroscopy optimized material, fabricated into pixelated sensors.

Recent advances in the development of high-resolution 3D cadmium–zinc–telluride drift strip detectors

“…Since the first spectroscopic grade detector was fabricated (Butler et al, 1992), CZT now represents the leading detector material over high-Z and wide-band-gap compound semiconductors (Del Sordo, 2004Sordo, , 2009 Takahashi & Watanabe, 2001;Turturici et al, 2014). Aside from its appealing physical properties (high atomic number, wide band gap, high density), this success can mainly be attributed to the important advancements in both crystal growth and device fabrication technologies (Abbene et al, 2016(Abbene et al, , 2020Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018;Szeles et al, 2008;Thomas et al, 2017;Veale et al, 2020;Zappettini et al, 2009).…”

Gamma‐Ray Detection Using Bi‐Poor Cs2AgBiBr6 Double Perovskite Single Crystals

“…The determined μ–τ product for Bi‐poor Cs 2 AgBiBr 6 SCs is 1.47 × 10 −3 cm 2 V −1 , which is slightly lower than that of the leading semiconductor detector material CdZnTe SCs (CdZnTe: ≈10 −2 cm 2 V −1 ). [ 25,26 ] Especially we observed that the μ–τ product has been raised from 5.19 × 10 −4 cm 2 V −1 for Bi‐normal Cs 2 AgBiBr 6 SCs to 1.47 × 10 −3 cm 2 V −1 for crystals grown from Bi‐poor 0.8 solutions. Such an improvement indicated Cs 2 AgBiBr 6 SCs grown from Bi‐poor solutions should have a preferable radiation detection performance compared with the Bi‐normal ones.…”

Room-temperature performance of 3 mm-thick cadmium–zinc–telluride pixel detectors with sub-millimetre pixelization

“…Nowadays, cadmium zinc telluride (CdZnTe or CZT) is a consolidated semiconductor material for room-temperature radiation detection (Del Sordo et al, 2009;Johns & Nino, 2019;Owens & Peacock, 2004;Takahashi & Watanabe, 2001). The success of this compound semiconductor for X-ray and gamma ray detection, aside from its appealing physical properties (high atomic number, wide band gap, high density), can mainly be attributed to the important advancements of crystal growth and device fabrication technologies (Abbene et al, 2016(Abbene et al, , 2020Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018;Szeles et al, 2008;Zappettini et al, 2009). Currently, the best spectroscopic-grade CZT crystals are fabricated using the travelling heater method (THM) growth technique (Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018;Veale et al, 2020).…”

“…The success of this compound semiconductor for X-ray and gamma ray detection, aside from its appealing physical properties (high atomic number, wide band gap, high density), can mainly be attributed to the important advancements of crystal growth and device fabrication technologies (Abbene et al, 2016(Abbene et al, , 2020Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018;Szeles et al, 2008;Zappettini et al, 2009). Currently, the best spectroscopic-grade CZT crystals are fabricated using the travelling heater method (THM) growth technique (Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018;Veale et al, 2020). If compared with other high-Z and wide-bandgap compound semiconductors (Del Sordo et al, 2009;Owens & Peacock, 2004), the charge transport properties of THMgrown CZT crystals are very impressive, with mobility-lifetime products of electrons e e greater than 10 À2 cm 2 V À1 .…”

“…the related electronic noise) to be as low as possible. Typically, CZT detectors are fabricated with quasi-ohmic electrical contacts (gold, platinum), allowing electric fields greater than 3000 V cm À1 (Chen et al, 2008;Iniewski, 2014;Prokesch et al, 2018), a moderate leakage current (< 20 nA cm À2 at 1000 V cm À1 ) (Awadalla et al, 2014;Bell et al, 2015) and no bias-induced polarization phenomena (Farella et al, 2009;Principato et al, 2013;Turturici et al, 2014).…”