Polarization Phenomena in CdTe Nuclear Radiation Detectors

Malm, Hedda; Martini, Mario

doi:10.1109/tns.1974.4327478

Cited by 117 publications

(39 citation statements)

References 10 publications

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“…Degradations occur more rapidly at high temperatures, at low bias voltages and for thick detectors, as widely shown in several works [10,[12][13][14][15][16][17]. Several solutions have been proposed to suppress polarization: high bias voltage operation, low temperature, low detector thickness, and switching off the bias voltage at regular time intervals.…”

Section: Introductionmentioning

confidence: 90%

“…Therefore, the high bias voltage operation and the fine segmentation of the electrodes of Al/CdTe pixel detectors make them very attractive for high-resolution spectroscopic imaging, recently proposed in astrophysics, diagnostic medicine, industrial imaging, and security screening. Time instability under bias voltage (generally termed as polarization) is the major drawback of CdTe diode detectors, as well documented in the literature [12][13][14].…”

Section: Introductionmentioning

confidence: 93%

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Electrical characterization of CdTe pixel detectors with Al Schottky anode

Turturici

Abbene

Gerardi

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tPixelated Schottky Al/p-CdTe/Pt detectors are very attractive devices for high-resolution X-ray spectroscopic imaging, even though they suffer from bias-induced time instability (polarization). In this work, we present the results of the electrical characterization of a (4 Â 4) pixelated Schottky Al/p-CdTe/Pt detector. Current-voltage (I-V) characteristics and current transients were investigated at different temperatures. The results show deep levels that play a dominant role in the charge transport mechanism. The conduction mechanism is dominated by the space charge limited current (SCLC) both under forward bias and at high reverse bias. Schottky barrier height of the Al/CdTe contact was estimated by using the thermionic-field emission model at low reverse bias voltages. Activation energy of the deep levels was measured through the analysis of the reverse current transients at different temperatures. Finally, we employed an analytical method to determine the density and the energy distribution of the traps from SCLC current-voltage characteristics.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 93%

Electrical characterization of CdTe pixel detectors with Al Schottky anode

Turturici

Abbene

Gerardi

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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“…This phenomenon has been widely studied for Si, Ge, and CdTe detectors 22,23 but up to now no quantitative analysis has been reported in literature on diamond based detectors. This phenomenon arises from changes with time in the electrical field in the active diamond intrinsic layer due to accumulation of space charge in deep trap levels during the application of the bias voltage.…”

Section: B Alpha Particles Spectramentioning

confidence: 99%

Characterization of damage induced by heavy neutron irradiation on multilayered L6iF-single crystal chemical vapor deposition diamond detectors

Almaviva

Angelone

Marinelli

et al. 2009

Journal of Applied Physics

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High performance neutron detectors sensitive to both thermal and fast neutrons are of great interest to monitor the high neutron flux produced, e.g., by fission and fusion reactors. An obvious requirement for such an application is neutron irradiation hardness. This is why diamond based neutron detectors are currently under test in some of these facilities. In this paper the damaging effects induced in chemical vapor deposition (CVD) diamond based detectors by a neutron fluence of ∼2×1016 neutrons/cm2 have been studied and significant changes in spectroscopic, electrical, and optical properties have been observed. The detectors are fabricated using high quality synthetic CVD single crystal diamond using the p-type/intrinsic/Schottky metal/L6iF layered structure recently proposed by Marinelli et al. [Appl. Phys. Lett. 89, 143509 (2006)], which allows simultaneous detection of thermal and fast neutrons. Neutron radiation hardness up to at least 2×1014 n/cm2 fast (14 MeV) neutron fluence has been confirmed so far [see Pillon et al., (Fusion Eng. Des. 82, 1174 (2007)]. However, at the much higher neutron fluence of ∼2×1016 neutrons/cm2 damage is observed. The detector response to 5.5 MeV A241m α-particles still shows a well resolved α-peak, thus confirming the good radiation hardness of the device but a remarkable degradation and a significant instability with time of charge collection efficiency and energy resolution arise. Symmetric, nearly Ohmic I-V (current-voltage) characteristics have been recorded from the metal/intrinsic/p-doped diamond layered structure, which before neutron irradiation acted as a Schottky barrier diode with a strong rectifying behavior. The nature and the distribution of the radiation induced damage have been deeply examined by means of cathodoluminescence spectroscopy. A more heavily damaged area into the intrinsic diamond at the same position and with the same extension of the L6iF layer has been found, the increased damage being ascribed to the highly ionizing particles produced in the L6iF layer by thermal neutrons through the nuclear reaction L6i(n,α)T.

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“…Early CdTe detectors suffered from polarisation; the progressive loss of sensitivity due to a time-dependent reduction in charge collection or depletion thickness (Bell et al 1974;Malm and Martini 1974;Siffert et al 1976), although more recent detectors have largely overcome this (Bojsen 1984;Frederick et al 1987). To identify any polarisation with the CdTe probe, counts were recorded using a SVCo source in a fixed geometry with a multi-channel analyser set to multiscaler mode.…”

Section: Materials and M E T H O D Smentioning

confidence: 99%

Evaluation of a technique for the intraoperative detection of a radiolabelled monoclonal antibody against colorectal cancer

et al. 1991

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Occult tumour deposits may be localised at operation with a radiation detecting probe following the administration of a radiolabelled monoclonal antibody (MoAb) recognising a tumour-associated antigen. We have recently evaluated the clinical usefulness of this technique in detecting primary colorectal tumours targetted with an indium-111 MoAb. In the present study the physical characteristics of the two detector systems used were investigated; a sodium iodide [NaI(Tl)] scintillation detector and a cadmium telluride (CdTe) semiconductor probe. Limitations of the technique in use have been examined by testing the statistical significance of tumour detection using an abdominal phantom based on the currently available clinical biodistribution data for tumour uptake of radiolabelled MoAbs. The effect of tumour volume, antibody uptake, collimation and counting conditions was examined. Results indicate that tumours of 10 ml volume may be detected with the NaI(Tl) probe at the lowest levels of radiolabelled antibody uptake currently reported in the literature but that at higher published levels, lesions as small as 1 ml may be identified with both detector systems. Detector sensitivity and limited antibody specificity restrict the usefulness of the technique, although moderate improvements in tumour uptake may allow the detection of tumour deposits not clinically apparent. The statistical significance criterion used for this study could be an accurate and reliable indicator for tumour detection in vivo.

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Polarization Phenomena in CdTe Nuclear Radiation Detectors

Cited by 117 publications

References 10 publications

Electrical characterization of CdTe pixel detectors with Al Schottky anode

Electrical characterization of CdTe pixel detectors with Al Schottky anode

Characterization of damage induced by heavy neutron irradiation on multilayered L6iF-single crystal chemical vapor deposition diamond detectors

Evaluation of a technique for the intraoperative detection of a radiolabelled monoclonal antibody against colorectal cancer

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