Improvement of CdMnTe Detector Performance by MnTe Purification

Kim, K. H.; Bolotnikov, A. E.; Camarda, G. S.; Tappero, Ryan; Hossain, Anwar; Cui, Yonggang; Yang, Ge; Gul, R.; James, R. B.

doi:10.1557/opl.2011.1272

Cited by 6 publications

(3 citation statements)

References 6 publications

(8 reference statements)

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“…In Figure 3(a), the DOCP was zero at  = 18. Furthermore, Figure 3(b) shows the Mn ions concentration on the sample surface, which was obtained by the PL peak photon energies at 300 K using the following equation [19] g ( ) = 1.528 + 1.316 [eV]. (3)…”

Section: Resultsmentioning

confidence: 99%

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Propagation effect on photoluminescence of spin-aligned high-density exciton magnetic polarons in Cd 0.8 Mn 0.2 Te

Nagata

Hirase

Miyajima

2017

Journal of Luminescence

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Section: Resultsmentioning

confidence: 99%

“…This redshift is resulted from a change in the bandgap energy. The bandgap energy was reported as a function of the Mn ion concentration x and the temperature T[19], for the range…”

mentioning

confidence: 99%

Propagation effect on photoluminescence of spin-aligned high-density exciton magnetic polarons in Cd 0.8 Mn 0.2 Te

Nagata

Hirase

Miyajima

2017

Journal of Luminescence

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“…Therefore, we chose stable MnTe compounds as starting material for purification. Details on purifying the material were described earlier [4]. We found that the performance of a CMT detector grown with two-times purified MnTe with Te solvent was improved.…”

Section: B Materials Purificationmentioning

confidence: 91%

New Approaches for Making Large-Volume and Uniform CdZnTe and CdMnTe Detectors

Kim

Bolotnikov

Camarda

et al. 2012

IEEE Trans. Nucl. Sci.

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Although CdZnTe (CZT) and CdMnTe (CMT) materials are leading contenders for room-temperature semiconductor detectors, nonetheless, both materials have limitations hindering their full usage in producing economical, uniform, large-volume devices due to their grain/twin boundaries, material purity, secondary-phase Te defects and material segregation. We tried to prevent the generation of twin and subgrain boundaries to achieve large-volume CZT crystals by means of local temperature control between the CZT melt and quartz crucible. Also, we have expanded the understanding of the electrical and structural properties of coherent/incoherent twin boundaries. The high residual impurities in the starting source materials, especially in manganese, were identified as obstacles against obtaining high-performance CMT detectors. We found that purifying manganese telluride (MnTe) via a floating Te melt-zone very effectively removes impurities, leading to better detectors. CMT detectors fabricated with purified material give a 2.1% energy resolution for 662 keV with a Cs gamma source without any electron-loss corrections. Secondary-phase Te defects deteriorate detector performance due to incomplete charge collection caused by charge trapping. In situ growth interface studies reveal the thermo-migration of Te inclusions to CZT melts and the dependence of Te-inclusion size on the cooling rate. The effective segregation coefficient of Zn in the CdTe host is nearly 1.3, so about 5%-6% of Zn deviation was reported in Bridgman-grown CZT (Zn 10% ingots. Such uncontrolled Zn variations cause a significant variation of the band-gap throughout the ingot and, consequently, affect the nonuniformity of the detectors' responses. Practically, this means that manufacturers cannot cut the ingot parallel to the crystal growth direction. We also demonstrated that the segregation of Zn can be controlled by creating particular thermal environments after growth.

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