The effects of chemical etching on the charge collection efficiency of {111} oriented Cd/sub 0.9/Zn/sub 0.1/Te nuclear radiation detectors

Wright, Gomez W.; Cui, Yunlong; Roy, Utpal; Barnett, C. F.; Reed, K.W.; Bürger, A.; Lu, Fengying; Li, L.; James, R. B.

doi:10.1109/tns.2002.803852

Cited by 29 publications

(19 citation statements)

References 9 publications

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“…These observations indicate that the ratio of the surface recombination velocity to the bulk lifetime is different on these two faces. Such a difference in the surface recombination velocity has already been reported by the other authors using DC photoconductivity measurements for samples of unspecified orientation [1] and for a (111) sample [2].…”

Section: B Tof Drift Mobility Measurementssupporting

confidence: 77%

“…The surface properties of CdZnTe samples subjected to several different surface preparation conditions have been extensively studied by measuring the direct-current (DC) photoconductivity response at several different photon energies, including below-gap as well as above-gap excitation [1]. Further, the influence of the surface preparation conditions, which determines the surface recombination velocity, on the gamma-ray spectra for relatively low-energy gamma photons has been demonstrated [2]. In general, the surface recombination velocity depends strongly on the crystallographic orientation of the material.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Surface Recombination Velocity on CdTe Radiation Detectors by Time-of-Flight Measurements

Suzuki¹,

Shiraki

2009

IEEE Trans. Nucl. Sci.

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The surface recombination velocity on high-resistivity CdTe with several different crystallographic orientations-(111), 5 off from (111), 8 off from (311), and (511)-has been investigated by using a " -model" spectral fitting method in combination with time-of-flight drift mobility measurement. In the samples orientated parallel to (111) and 5 off from (111), the Cd face exhibits a higher surface recombination velocity ( 6 10 5 cm/s) than the Te face ( 3 10 5 cm/s). Away from the polar face and toward the (511) face, the difference is less pronounced, although not completely absent.

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Section: B Tof Drift Mobility Measurementssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Evaluation of Surface Recombination Velocity on CdTe Radiation Detectors by Time-of-Flight Measurements

Suzuki¹,

Shiraki

2009

IEEE Trans. Nucl. Sci.

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“…Differences between the two sides may be expected in orientated crystals. For example, Wright et al [7] have shown that for Cd-and Teterminated surfaces, surface processing conditions significantly affect surface recombination velocities underneath the electrodes, which in turn affect the electron and hole charge collection efficiencies. The resulting differences in the electron mu-tau product can be as great as 25%.…”

Section: Detector Fabricationmentioning

confidence: 99%

Hard X- and γ-ray measurements with a large volume coplanar grid CdZnTe detector

Owens

Buslaps

Gostilo

et al. 2006

Nuclear Instruments and Methods in Physics Research Section A:

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The recent introduction of coplanar grid techniques has led to resurgence in interest in developing large volume compound semiconductor detectors that have a reasonable g-ray response but also good spectroscopic resolution. We report the results of a series of hard X-and g-ray measurements on a large 15 Â 15 mm 2 , 10 mm thick CdZnTe coplanar grid detector. The measurements were carried out at the HASYLAB and ESRF synchrotron radiation facilities using highly monochromatic pencil beams across the energy range 20-800 keV. Additional full-area measurements were carried out using radioactive sources. All measurements were carried out at room temperature. The measured energy resolution under full-area illumination was 8 and 12 keV FWHM at 59.95 and 662 keV, respectively. Under pencil beam illumination, the measured resolutions were essentially the same. The detector energy response function was found to be linear over the energy range 20-1400 keV with an average rms nonlinearity of 1.4%, consistent with statistics. The spatial uniformity of the detector was evaluated at 30, 60 and 180 keV by raster scanning a 20 Â 20 mm 2 monoenergetic X-ray beam across the active area. Apart from a few localized areas, the detector response was found to uniform at the few percent level, consistent with statistics. At 180 keV, the nonuniformity in the energy response due to the grids was estimated to be at the 0.7% level.

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“…Singlecrystal volumes exceeding 100 cm 3 are routinely produced (the largest twin-free single crystal size is about 300cm 3 ). One of the important new developments attributed to YinnelTech's research [1,2] is the emergence of a process to intentionally introduce impurities into the ingot to reduce the deleterious effects of the native defect concentrations (i.e., cadmium vacancies and tellurium anti-sites) [9]. High electrical resistivities of ingots, which are comparable to or in excess of those obtained with high-pressure Bridgman methods, are now obtained.…”

Section: Czt Crystal Growthmentioning

confidence: 99%

“…After measuring the intergrid resistances on both sides, the grids and the guard rings on the Te side were short-circuited, forming a solid cathode electrode [8,9].…”

Section: Detector Fabricationmentioning

confidence: 99%

Preliminary Results of Large Volume Multi-Pair Coplanar Grid CdZnTe Detector Fabrication

Gostilo

He²,

Иванов³

et al.

IEEE Nuclear Science Symposium Conference Record, 2005

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We present electrode fabrication techniques and preliminary test results of a multi-pair coplanar grid CdZnTe detector with a volume of 11 cm 3 , the largest single CdZnTe device ever fabricated. The crystal of initial dimensions 30.5x32.9x17.3 mm 3 was grown by modified vertical Bridgman technique. The peculiarities of the growing process are analyzed.Crystal has high bulk resistivity of ρ=1x10 11 Ohm*cm, a value of (µτ) e = 5.6x10 -3 cm 2 /V and a value of electron mobility µ e = 675 cm 2 /Vs. Non-uniformity of material was found as result of crystal input test.Intergrid resistivity on all four segments of electrode structure was about 0.4 GOhm and 0.2 GOhm on Cd and Te side respectively. These values are significantly lower than that in our previous development. Dependences of resistivity on technological modes of passivation and on applied voltage are presented. Leakage current in all segments of detector did not exceed 10 nA at bias 1200 V. Spectra Cs-137 for all four segments of detector structure are presented.

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The effects of chemical etching on the charge collection efficiency of {111} oriented Cd/sub 0.9/Zn/sub 0.1/Te nuclear radiation detectors

Cited by 29 publications

References 9 publications

Evaluation of Surface Recombination Velocity on CdTe Radiation Detectors by Time-of-Flight Measurements

Evaluation of Surface Recombination Velocity on CdTe Radiation Detectors by Time-of-Flight Measurements

Hard X- and γ-ray measurements with a large volume coplanar grid CdZnTe detector

Preliminary Results of Large Volume Multi-Pair Coplanar Grid CdZnTe Detector Fabrication

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