Incomplete Charge Collection at Inter-Pixel Gap in Low- and High-Flux Cadmium Zinc Telluride Pixel Detectors

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 4; p. 1441
• Main Authors: Buttacavoli, Antonino, Principato, Fabio, Gerardi, Gaetano, Cascio, Donato, Raso, Giuseppe, Bettelli, Manuele, Zappettini, Andrea, Seller, Paul, Veale, Matthew C, Abbene, Leonardo
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.02.2022; MDPI
• Subjects: Arrays; Cadmium; Cadmium Compounds - chemistry; Cadmium zinc tellurides; charge sharing; Charge transport; charge-sharing correction; Crystals; CZT detectors; Detectors; Digital electronics; Electrodes; Energy; Energy spectra; Hole mobility; incomplete charge collection; Noise; Nondestructive testing; Photons; Pixels; Radiation; Room temperature; semiconductor pixel detectors; Sensors; Tellurium - chemistry; Transport properties; X ray imagery; X-Rays; Zinc - chemistry; Zinc telluride; Zinc tellurides; United Kingdom; United Kingdom > UK; Canada; Italy; charge-sharing correction; charge sharing; semiconductor pixel detectors; incomplete charge collection; CZT detectors
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22041441

The success of cadmium zinc telluride (CZT) detectors in room-temperature spectroscopic X-ray imaging is now widely accepted. The most common CZT detectors are characterized by enhanced-charge transport properties of electrons, with mobility-lifetime products μeτe > 10 cm /V and μhτh > 10 cm /V. These materials, typically termed low-flux LF-CZT, are successfully used for thick electron-sensing detectors and in low-flux conditions. Recently, new CZT materials with hole mobility-lifetime product enhancements (μhτh > 10 cm /V and μeτe > 10 cm /V) have been fabricated for high-flux measurements (high-flux HF-CZT detectors). In this work, we will present the performance and charge-sharing properties of sub-millimeter CZT pixel detectors based on LF-CZT and HF-CZT crystals. Experimental results from the measurement of energy spectra after charge-sharing addition (CSA) and from 2D X-ray mapping highlight the better charge-collection properties of HF-CZT detectors near the inter-pixel gaps. The successful mitigation of the effects of incomplete charge collection after CSA was also performed through original charge-sharing correction techniques. These activities exist in the framework of international collaboration on the development of energy-resolved X-ray scanners for medical applications and non-destructive testing in the food industry.