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

Zappettini, A.; Marchini, L.; Zha, M.; Benassi, G.; Zambelli, N.; Calestani, Davide; Zanotti, L.; Gombia, E.; Mosca, R.; Zanichelli, M.; Pavesi, M.; Auricchio, N.; Caroli, E.

doi:10.1109/tns.2011.2163643

Cited by 37 publications

(17 citation statements)

References 23 publications

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“…An innovative CZT growth technique, named the boron oxide encapsulated vertical Bridgman technique, has been recently implemented at CNR/IMEM (Parma, Italy). 1,2 The main feature of this technique is that the crystal, during growth, is fully encapsulated by a thin layer of liquid boron oxide, so that the contact between the crystal and the crucible is prevented. The stress of the crucible to the crystal is also strongly reduced during cooling, because the boron oxide layer is molten down to about 500 C. In this case, grade crystals with large single grains and a lower dislocation density were obtained.…”

Section: Introductionmentioning

confidence: 99%

Charge transport properties in CdZnTe detectors grown by the vertical Bridgman technique

Auricchio¹,

Marchini²,

Caroli³

et al. 2011

Journal of Applied Physics

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Hard x-ray response of pixellated CdZnTe detectorsPresently, a great amount of effort is being devoted to the development of CdTe and CdZnTe (CZT) detectors for a large variety of applications such as medical, industrial, and space research. We present the spectroscopic properties of some CZT crystals grown by the standard vertical Bridgman method and by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR (Parma, Italy). In this technique, the crystal is grown in an open quartz crucible fully encapsulated by a thin layer of liquid boron oxide. This method prevents contact between the crystal and the crucible, thereby allowing larger single grains with a lower dislocation density to be obtained. Several mono-electrode detectors were realized, with each having two planar gold contacts. The samples are characterized by an active area of about 7 mm Â 7 mm and thicknesses ranging from 1 to 2 mm. The charge transport properties of the detectors have been studied by mobility-lifetime (l Â s) product measurements, carried out at the European Synchrotron Radiation Facility (Grenoble, France) in the planar transverse field configuration, where the impinging beam direction is orthogonal to the collecting electric field. We have performed several fine scans between the electrodes with a beam spot of 10 lm Â 10 lm at various energies from 60 to 400 keV. In this work, we present the test results in terms of the (l Â s) product of both charge carriers.

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Section: Introductionmentioning

confidence: 99%

Charge transport properties in CdZnTe detectors grown by the vertical Bridgman technique

Auricchio¹,

Marchini²,

Caroli³

et al. 2011

Journal of Applied Physics

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“…This detector was glued with silver paste on a lexan support and bonded with Au wire of 25 11m to the electrodes [3], as we can see in Fig. 4.…”

Section: Twin Shaping Time Methodsmentioning

confidence: 99%

Twin shaping filter technique for signals compensation in CZT detectors grown by the Vertical Bridgman method

Auricchio

Caroli

Marchini

et al. 2011

2011 IEEE Nuclear Science Symposium Conference Record

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CdTe/CdZnTe is a consolidated material to realize detectors for a large variety of applications, such as medical, industrial, and space research. An Italian collaboration, involving the CNRlIMEM and INAFIIASF institutes, was born some years ago with the aim to develop a national capability to produce CZT detectors starting from the material growth to the final detection device. Some important features of these detectors (pulse height, energy resolution, photopeak efficiency) are affected by the charge collection efficiency: the low mobility of the charge carriers (particularly the holes) and trapping/detrapping phenomena can degrade the CdTe/CZT detectors response, depending on the distance between the charge formation position and the collecting electrodes. Several efforts have been made to improve the detection efficiency as well as the energy resolution, using both the optimization of the electrode geometry (drift strip technique, coplanar-grid, small pixel effect) and pulse height compensation methods to overcome the hole trapping problem. We have studied a bi-parametric method that uses a twin pulse shaping active filter to analyze the same signal: one slow, which is proportional to the energy of the photon, and one fast, which depends on the position of the interaction with respect to the collecting electrode. The experimental results obtained with the application of this bi-parametric technique on planar CZT detectors of good quality grown by the Vertical Bridgman method at CNRlIMEM are presented as a function of the bias voltage, photon energy and shaping time pairs.

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“…We have chosen 4 CZT crystals grown by the standard vertical Bridgman method [1] and 2 CZT crystals grown by the boron oxide encapsulated vertical Bridgman method [2].…”

Section: Czt Crystalsmentioning

confidence: 99%

Charge transport properties in CZT detectors grown by the vertical bridgman technique

Auricchio

Marchini

Caroli

et al. 2010

IEEE Nuclear Science Symposuim &Amp; Medical Imaging Conference

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Great efforts are being presently devoted to the development of CdTe and CdZnTe detectors for a large variety of applications, such as medical, industrial, and space research. We present the spectroscopic properties of some CZT crystals grown by the standard vertical Bridgman method and by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR (Parma, Italy). By this technique the crystal is grown in an open quartz crucible fully encapsulated by a thin layer of liquid boron oxide. This method prevents contact between the crystal and the crucible thereby allowing larger single grains with a lower dislocation density to be obtained. Several mono-electrode detectors were realized each with two planar gold contacts. The samples are characterized by an active area of about 7 mm x 7 mm and thicknesses ranging from 1 to 2 mm. The charge transport properties of the detectors have been studied by mobility-lifetime (µt) product measurements, carried out at the European Synchrotron Radiation Facility (Grenoble) in the PTF configuration, where the impinging beam direction is orthogonal to the collecting electric field. We have performed several fine scans between the electrodes with a beam spot of 10 µm x10 µm at various energies from 60 keV to 400 keV. In this work we present the test results in terms of µt product of both charge carriers.

show abstract

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

Cited by 37 publications

References 23 publications

Charge transport properties in CdZnTe detectors grown by the vertical Bridgman technique

Charge transport properties in CdZnTe detectors grown by the vertical Bridgman technique

Twin shaping filter technique for signals compensation in CZT detectors grown by the Vertical Bridgman method

Charge transport properties in CZT detectors grown by the vertical bridgman technique

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