Simulation, modeling, and crystal growth of Cd0.9Zn 0.1Te for nuclear spectrometers

Krishna C. Mandal, Sung Hoon Kang, Michael Choi, Job Bello, Lili Zheng, Hui Zhang, Michael Groza, Utpal N. Roy, Arnold Burger, Gerald E. Jellison, David E. Holcomb, Gomez W. Wright, Joseph A. Williams

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd0.9Zn0.1Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor materials (Cd, Zn, and Te). A state-of-the-art computer model, multizone adaptive scheme for transport and phase-change processes (MASTHAP), is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in the as-grown CZT crystal and optimize the thermal profile. The model accounts for heat transfer in the multiphase system, convection in the melt, and interface dynamics. The grown semi-insulating (SI) CZT crystals have demonstrated promising results for high-resolution room-temperature radiation detectors due to their high dark resistivity (p ≈2.8 × 1011 Ωcm), good charge-transport properties [electron and hole mobility-life-time product, μτe ≈ (2-5) × 10-3 and μτh ≈ (3-5) × 10 -5 respectively, and low cost of production. Spectroscopic ellipsometry and optical transmission measurements were carried out on the grown CZT crystals using two-modulator generalized ellipsometry (2-MGE). The refractive index n and extinction coefficient k were determined by mathematically eliminating the ∼3-nm surface roughness layer. Nuclear detection measurements on the single-element CZT detectors with 241Am and 137Cs clearly detected 59.6 and 662 keV energies with energy resolution (FWHM) of 2.4 keV (4.0%) and 9.2 keV (1.4%), respectively.

Original languageEnglish
Pages (from-to)1251-1256
Number of pages6
JournalJournal of Electronic Materials
Volume35
Issue number6
DOIs
StatePublished - Jun 2006

Funding

Financial support for this work was provided by EIC. The authors thank Mr. Gerardo J. Pena for assistance in CZT crystal processing and Dr. R. David Rauh for useful discussion.

Keywords

  • 2-MGE
  • Bridgman technique
  • CZT
  • MASTRAP model
  • Radiation detectors

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