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Title: Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC)

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
929832
Report Number(s):
BNL-80396-2008-JA
Journal ID: ISSN 0255-5476; MSFOEP; TRN: US200822%%904
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Science Forum; Journal Volume: 508
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL GROWTH; CRYSTAL GROWTH METHODS; CRYSTALLIZATION; CADMIUM TELLURIDES; national synchrotron light source

Citation Formats

Su,C., Lehoczky, S., Li, C., Ragothamachar, B., Dudley, M., Szoke, J., and Barczy, P.. Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC). United States: N. p., 2006. Web. doi:10.4028/www.scientific.net/MSF.508.117.
Su,C., Lehoczky, S., Li, C., Ragothamachar, B., Dudley, M., Szoke, J., & Barczy, P.. Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC). United States. doi:10.4028/www.scientific.net/MSF.508.117.
Su,C., Lehoczky, S., Li, C., Ragothamachar, B., Dudley, M., Szoke, J., and Barczy, P.. Sun . "Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC)". United States. doi:10.4028/www.scientific.net/MSF.508.117.
@article{osti_929832,
title = {Crystal Growth of CdTe by Gradient Freeze in Universal Multizone Crystallizator (UMC)},
author = {Su,C. and Lehoczky, S. and Li, C. and Ragothamachar, B. and Dudley, M. and Szoke, J. and Barczy, P.},
abstractNote = {No abstract prepared.},
doi = {10.4028/www.scientific.net/MSF.508.117},
journal = {Materials Science Forum},
number = ,
volume = 508,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • The generation and multiplication of dislocations in an indium phosphide (InP) single crystal grown by the vertical gradient freeze (VGF) process is predicted using a crystallographic model. This model couples microscopic dislocation motion and multiplication to macroscopic plastic deformation during the crystal growth process. During growth of an InP crystal, dislocations are generated in the plastically deformed crystal as a result of crystallographic glide caused by excessive thermal stresses. The temperature fields are determined by solving the partial differential equation of heat conduction in a VGF crystal growth system. The effects of growth direction and growth parameters (i.e., imposed temperaturemore » gradients, crystal radius and growth rate) on dislocation generation and multiplication in an InP crystal are investigated. Dislocation density patterns on the cross section of an InP crystal are numerically calculated and compared with experimental observations.« less
  • The Universal Multizone Crystallizator (UMC) is a special apparatus for crystal growth under terrestrial and microgravity conditions. The use of twenty-five zones allows the UMC to be used for several normal freezing growth techniques. The thermal profile is electronically translated along the stationary sample by systematically reducing the power to the control zones. Elimination of mechanical translation devices increases the systems reliability while simultaneously reducing the size and weight. This paper addresses the UMC furnace design, sample cartridge and typical thermal profiles and corresponding power requirements necessary for the dynamic gradient freeze crystal growth technique. Results from physical vapor transportmore » and traveling heater method crystal growth experiments are also discussed.« less
  • The growth-tip region of a high-purity 4.2-cm diameter Ge boule grown using low-pressure Bridgman methods in a vertical gradient freeze furnace was sectioned and polished in preparation for scanning electron microscopy and was characterized using electron backscatter diffraction (EBSD). The boule had a characteristic conical tip region with cone angle of 40° of a right circular cylinder from which a section was taken along the boule longitudinal centerline with an approximate surface area of 4 cm 2. The majority of this surface area was characterized using EBSD and an image collage was assembled for the tip region. The grain structure,more » grain boundary orientation, twin structure, and overall crystal growth direction were determined. A crystal growth direction of approximately <112> was observed, which was also identified as the growth direction of several prominent twins observed in the tip region. The grain structure of the tip region appeared to be controlled by the sidewall nucleation of a stray grain that competed for dominance during growth. Grain boundaries and triple grain junctions were identified as low-energy coincident-site-lattice (CSL) boundaries and junctions of the Σ3 and Σ9 types.« less
  • The CrysMAS code of the Crystal Growth Laboratory, Fraunhofer IISB, is applied to reveal conditions occurring in electrodynamic gradient freeze furnaces during the growth of cadmium zinc telluride crystals. Of particular interest are heat transfer and growth conditions associated with crucibles of different design, one constructed of graphite and the other of pyrolytic boron nitride (PBN). Under identical furnace set-point schedules, the PBN system exhibits very different heat transfer through the cone region of the crucible, resulting in steeper axial thermal profiles and convex solid-interface shapes (rather than the concave shapes computed for the graphite crucible). Both systems exhibit amore » concave interface during growth through the cylindrical part of the crucible; however, the axial thermal profile through the contents of the graphite crucible is considerably more offset from the set-point profile of the furnace due to the large axial flows of heat through the crucible walls. These conditions argue for advantage to the PBN system; however, comparatively larger radial gradients in the PBN system could lead to higher dislocation levels.« less
  • Electron backscatter diffraction (EBSD) was used to characterize the growth-tip region of a 4.2-cm diameter CdZnTe (CZT) boule grown using low-pressure Bridgman method in a vertical gradient freeze furnace. The boule was sectioned and polished and a section taken along the boule longitudinal centerline with an approximate surface area of 1-cm 2 was used for optical and scanning electron microscopy. A collage was assembled using EBSD/SEM images to show morphological features, e.g., twin structure, grain structure, and overall crystal growth direction. Severely twinned regions originating from the tip and side walls were observed. The overall growth orientation was close tomore » (1 1 0) and (1 1 2) directions. In some regions, the (0 0 1) poles of the CZT matrix aligned with the growth direction, while twins aligned such that (1 1 1) and (1 1 2) poles aligned with the growth direction. Finally, in some other areas, (1 1 2) or (0 1 1) poles of the CZT matrix aligned with the growth direction. New relationships between the CZT matrix and large Te polycrystalline particles were revealed: {1 1 2 -} CZTΙΙ{1 1 - 0 0} Te and {0 0 1} CZTII{0 1 -1 -1} Te.« less