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The II-VI compound semiconductor cadmium zinc telluride (CZT) is very useful for room temperature radiation detection applications. In the present research, we have successfully grown Bi doped CZT single crystals with two different zinc concentrations (8 and 14 at. %) by the Bridgman oscillation method, in which one experiment has been carried out with a platinum (Pt) tube as the ampoule support. Pt also acts as a cold finger and reduces the growth velocity and enhances crystalline perfection. The grown single crystals have been studied with different analysis methods. The stoichiometry was confirmed by energy dispersive by x-ray and inductively coupled plasma mass spectroscopy analyses and it was found there is no incorporation of impurities in the grown crystal. The presence of Cd and Te vacancies was determined by cathodoluminescence studies. Electrical properties were assessed by I-V analysis and indicated higher resistive value (8.53 x 108 Ω cm) for the crystal grown with higher zinc concentration (with Cd excess) compare to the other (3.71 x 105 Ω cm) [ABSTRACT FROM AUTHOR]

Abstract: Photoluminescence (PL) from the vapour deposited layers of CdTe have demonstrated a unique quality improvement after as-grown samples have been annealed at relatively low temperatures (500–600 ∘C). The sub-band gap emissions at 4.2 K have been centred at the 1.42 and 1.47 eV and they have different intensity-power dependencies. This is strong evidence that they originate from the recombination of various defects. Similar deep-level defect emissions in bulk CdTe arise in the region of the so-called A-centre PL band (1.42 eV), and extended defect emissions (1.47 eV). The latter emission demonstrates a super-linear excitation-power dependence that is a characteristic of the excitonic recombination processes. After a short annealing at 500 ∘C the extended defect emission practically disappeared making possible observation of the band-to-band recombination at 1.58 eV. As a result of this work optimal annealing conditions have been found for the as-grown samples of CdTe on various substrates (Si, sapphire). [Copyright &y& Elsevier]

Abstract: The II–VI compound semiconductor crystal cadmium zinc telluride (CZT) is very important in the field of room-temperature radiation detectors and medical imaging applications. In the present study, bulk CZT single crystal has been grown by (i) oscillatory Bridgman technique, (ii) from vapour phase using pyrolytic boron nitride ampoule in the Bridgman geometry, and (iii) by using a Pt tube used for the ampoule support as a cold finger. Several improvements were found in the thermal environments such as the effects of superheating and reduced growth velocity, as well as improvements in the grain size and zinc composition along the ingot. The compositional homogeneity and its current–voltage characteristic behaviour have been analysed using energy dispersive X-ray analysis and I–V method, respectively. [Copyright &y& Elsevier]

Abstract: Cadmium zinc telluride (Cd1− x Zn x Te) epitaxial layers were grown by vapor phase epitaxy (VPE) to obtain material suitable for applications in photonics and radiation detectors. The VPE experiments were carried out in the modified Pfeiffer Classic 500 coating system, using Si 6-in substrates and Cd1− x Zn x Te ternary sources grown by the Bridgman method. To study the effect of source composition, the Cd1− x Zn x Te sources and as-grown layers were characterized by a scanning electronic microscopy (SEM), composition analysis (EDAX) and X-ray diffractometry (XRD). It was shown that the prolonged VPE growth is followed by the continuous deterioration of source composition that results in an inhomogeneous enrichment of Cd1− x Zn x Te layers with Zn. Nevertheless, the fast VPE runs using the sources in the form of thin polycrystalline wafers provide the uniform Cd1− x Zn x Te layers that could be considered for applications. [Copyright &y& Elsevier]

Abstract: Cadmium telluride (CdTe) crystals and epitaxial layers were grown by the vertical Bridgman method and vapor-phase epitaxy, respectively, to obtain the high-resistive material suitable for X- and gamma-ray detectors. The crystals and layers were doped with Ge at the concentration of 5×1017 cm−3 and co-doped with the rare element Yb at the concentration range from 1×1017 to 1×1019 cm−3. The CdTe:Ge:Yb samples were studied by the structural and electrical characterization techniques, low-temperature photoluminescence (PL) and cathodoluminescence (CL) spectroscopy and CL imaging. Experimental findings testify that homogeneous crystals and layers of reasonably good structural quality can be grown with the Yb concentration below the value of 5×1018 cm−3 that is estimated to be the limit for Yb solubility in CdTe:Ge:Yb. These findings seem to be related with the purification effect caused by the interaction of the Yb dopant with the group I residual impurities. [Copyright &y& Elsevier]