Evaluation of CZT crystals from the former Soviet Union

Abstract

Keywords: Cadmium Zinc Telluride (CZT), room temperature xadiation detectors, (PL), X-ray diffraction @D), pardcle-~duced X-ray emission (PIXE), crystal growt& ABSTR4CTVertical high pressure Bridgman (VHPB) Cdl-#UTe (0.04< x < 0.24) detector crystaIs grown m the Ukraine and Russia have been evahated and compared to U.S.-grown materials. Various analytical techniques were used to study the materials for trace impurities, precipitates, crystallinity, and electrical transport properties. Relatively high concentrations of carbon and trace impurities such as Se, Nd and Si have been detected in the crystals. In most cases, the crystals showed lower resistivity than U.S.-grown CZT. However, recent crystals grown in Russia exhibited better detector performance than those grown in prior years, and good response to an '*k radioactive source was found. Electron Metimes below 1 ps were measured in crystaIs having significant numbers of micro-defects, compared to lifetimes of 5-15 ps found in spectrometer grade materials produced in the U.S. Furthermore, the zinc composition along the growth axis showed better homogeneity m comparison with the U.S. material.

Growth and anisotropy of transport properties of detached Cd0.78Zn0.22Te crystals

“…Although the potential of CdZnTe for producing relatively large-volume gamma-ray spectrometers has been well demonstrated [1], numerous problems remain associated with growth process [2][3][4][5][6]. Crystal growth of CdZnTe is performed mainly by highpressure vertical Bridgman (HPVB) and low-pressure horizontal or vertical Bridgman (LPB) method [7][8][9][10][11][12][13]. All the investigators who grew crystals under microgravity conditions have observed the growth of crystals without contact with the crucible.…”

<title>Characterization of CZT detectors grown from horizontal and vertical Bridgman</title>

“…Crystal growth of CZT for producing gamma-ray detectors is being performed mainly by a high-pressure vertical Bridgman (HPVB) process. Recently, low-pressure horizontal and vertical Bridgman (LPB) crystals became commercially available, and spectrometric grade detectors were fabricated mainly from HPVB CZT and tested by several groups [1,[6][7][8][9][10][11][12]. Many papers have been published to characterize the various HPVB grown CZT crystals produced commercially in the US.…”

Growth and Characterization of CZT Crystals by the Vertical Bridgman Method for X-Ray Detector Applications

“…At lower energy, a large band is present, centered at 1.07 eV. This band is sometimes attributed to tellurium vacancies [16], [17]. Also iron, that is actually present in our crystals in low concentration, was reported to produce an emission band in this region [18], [19].…”