Boron oxide fully encapsulated CdZnTe crystals grown by the vertical Bridgman technique

Zappettini, A.; Zha, M.; Pavesi, M.; Zanotti, L.

doi:10.1016/j.jcrysgro.2007.07.012

Cited by 40 publications

(26 citation statements)

References 22 publications

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“…In an effort to develop a procedure to grow ingots with high purity and large single grains, a new Bridgman configuration for growth of CZT crystals 5,6 was studied in our laboratories. In contrast to the standard vertical Bridgman technique, the crystal is grown in an open ampoule, melt decomposition being prevented by use of a boron oxide layer and an opportune counterpressure of inert gas.…”

Section: Introductionmentioning

confidence: 99%

On the Role of Boron in CdTe and CdZnTe Crystals

Pavesi

Marchini

Zha

et al. 2011

Journal of Elec Materi

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It is well known that group III elements act as donors if they play a substitutional role at the metallic site in II-tellurides; nevertheless, several studies report both on the creation of complexes with vacancies, named A-centers, and on the involvement in self-compensation mechanisms, especially for indium. The boron concentration in II-tellurides is negligible, and its contribution to transport mechanisms has not been studied yet. For the last few years the authors have been developing a new technique to grow CdZnTe by the vertical Bridgman technique, taking advantage of encapsulation by means of boron oxide. In this way, crystals characterized by large single grains, low etch pit density, and high resistivity have been obtained. Recently, x-ray detectors with state-of-the-art performance have been produced from such crystals. Boron contamination, as a consequence of this growth method, is quite low but at least one order of magnitude above values obtained with other growth techniques. Besides being a low-cost technique which is also suitable for largescale mass production, the encapsulated vertical Bridgman technique is quite useful to prevent dislocations, grain boundaries, and stacking faults; for these reasons, careful characterization was performed to understand the effect of boron both on the electrical properties and on the spectroscopic performance of the final crystals. Our characterization is mainly based on low-temperature photoluminescence in addition to electrical current-voltage measurements, photostimulated current, and x-ray spectroscopy. The results indicate that boron behaves like other group III elements; in fact, boron forms a complex that does not affect the good performance of our x-ray detectors, even if it shows some properties which are typical of A-centers.

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Section: Introductionmentioning

confidence: 99%

On the Role of Boron in CdTe and CdZnTe Crystals

Pavesi

Marchini

Zha

et al. 2011

Journal of Elec Materi

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“…We used three types of detectors obtained from different manufacturers: one Pb-doped CdZnTe detector (vertical Bridgman method), 6 two Bi-doped CdZnTe detectors (vertical Bridgman method with two different dopant concentrations), 7 and an In-doped CdZnTe detector (Bridgman method). 2 The Zn concentration in these detectors was 10%.…”

Section: Methodsmentioning

confidence: 99%

Point Defects in Pb-, Bi-, and In-Doped CdZnTe Detectors: Deep-Level Transient Spectroscopy (DLTS) Measurements

Gul

Keeter

Rodriguez

et al. 2011

Journal of Elec Materi

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We studied, by current deep-level transient spectroscopy (I-DLTS), point defects induced in CdZnTe detectors by three dopants: Pb, Bi, and In. Pb-doped CdZnTe detectors have a new acceptor trap at around 0.48 eV. The absence of a V Cd trap suggests that all Cd vacancies are compensated by Pb interstitials after they form a deep-acceptor complex [[Pb Cd ] + -V Cd 2À ] À . Bi-doped CdZnTe detectors had two distinct traps: a shallow trap at around 36 meV and a deep donor trap at around 0.82 eV. In detectors doped with In, we noted three well-known traps: two acceptor levels at around 0.18 eV (A-centers) and 0.31 eV (V Cd ), and a deep trap at around 1.1 eV.

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“…1a). Details of the growth procedure were given elsewhere [10]. Experimental evidences suggest that the crystal grows according to the configuration shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Surprisingly, the whole crystal resulted to be encapsulated by a boron oxide layer, so that the crystal grows without direct contact with the crucible walls [10]. Thanks to this effect, 1-and 2-in crystals with large singlecrystal yield were grown, characterized by extremely low EPD (down to 1.5 Â 10 3 cm À2 ).…”

Section: Introductionmentioning

confidence: 99%