Room-temperature X-ray response of cadmium–zinc–telluride pixel detectors grown by the vertical Bridgman technique

Abstract

In this work, the spectroscopic performances of new cadmium–zinc–telluride (CZT) pixel detectors recently developed at IMEM‐CNR of Parma (Italy) are presented. Sub‐millimetre arrays with pixel pitch less than 500 µm, based on boron oxide encapsulated vertical Bridgman grown CZT crystals, were fabricated. Excellent room‐temperature performance characterizes the detectors even at high‐bias‐voltage operation (9000 V cm−1), with energy resolutions (FWHM) of 4% (0.9 keV), 1.7% (1 keV) and 1.3% (1.6 keV) at 22.1, 59.5 and 122.1 keV, respectively. Charge‐sharing investigations were performed with both uncollimated and collimated synchrotron X‐ray beams with particular attention to the mitigation of the charge losses at the inter‐pixel gap region. High‐rate measurements demonstrated the absence of high‐flux radiation‐induced polarization phenomena up to 2 × 106 photons mm−2 s−1. These activities are in the framework of an international collaboration on the development of energy‐resolved photon‐counting systems for high‐flux energy‐resolved X‐ray imaging.

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).…”

Energy Recovery of Multiple Charge Sharing Events in Room Temperature Semiconductor Pixel Detectors

“…Intense investigations have been made on the effects of charge-sharing and cross-talk phenomena in CZT and CdTe pixel detectors [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Charge-sharing events are generated by the splitting of the charge cloud created by a single interacting event and collected by two or more pixels.…”

“…However, as widely shown in both CdTe and CZT pixel detectors, charge losses at the inter-pixel gap often create incomplete energy recovery after CSA [ 17 , 18 , 19 ]. Recently, an energy-recovery technique for double charge shared events ( m = 2) was proposed by our group [ 20 ] and successfully applied to several CZT and CdTe pixel detectors [ 20 , 21 , 22 , 23 , 24 , 25 ]. Despite the benefits on detector performance, this technique can only be applied to shared events involving only two adjacent pixels ( m = 2) and, therefore, multiple coincidences with m > 2 and coincidences with diagonal pixels are rejected from the measured energy spectra.…”

Fabrication of Small-Pixel CdZnTe Sensors and Characterization with X-rays

“…CdZnTe grown at IMEM-CNR (Parma, Italy) by Boron oxide encapsulated vertical Bridgman technique has already demonstrated optimal performance, both with a single-pixel contact geometry [ 20 ] and sub-millimeter pixel geometry (500 and 250 pitch) [ 21 ]. The excellent spectroscopic performance of this material and the absence of radiation-induced polarization effects up to fluxes of photons motivated the decision to test CdZnTe grown at IMEM-CNR for synchrotron application.…”