Title: Effects of excess Te on flux inclusion formation in the growth of cadmium zinc telluride when forced melt convection is applied

Abstract

The presence of second phase defects, particularly flux inclusions of tellurium rich composition, are of great concern for charge collection efficiency in cadmium zinc telluride (CZT) and cadmium telluride (CT) material intended for applications such as radiation detection. These inclusions can distort applied electric field lines within the detector as well as act as trapping centers for charge carriers. Reduction and/or elimination of these inclusions is required to achieve appropriate charge collection efficiencies, especially in detectors of thicknesses greater than 5 mm. These so-called flux inclusions are understood to form as a consequence of constitutional undercooling at the crystal growth interface. In this study, a forced melt convection technique was applied in Vertical Bridgman (VB) melt growth of CZT without reducing imposed growth rates of ~2 mm/hr. Several rotation profiles were tested while adjusting the melt composition from 51.62 to 61.75 atomic percent (at%) Te where the Te concentration was initially increased to improve overall material purity. With forced melt convection, the best inclusion distributions were achieved with highly Te rich melt compositions, far beyond the stoichiometric composition range for the CZT system. Average inclusion diameters were reduced to 2 µm while inclusions greater than 5 µm were essentially eliminated.more » Composition analyses of these ingots revealed near equilibrium concentrations of Te, even with ingots grown from Te concentrations as high as 61.75 at% Te. In this paper, a recipe for the reduction of inclusions in CZT melt growth is put forward and the implications of this method on our understanding of inclusion formation are discussed.« less

Authors:

McCoy, Jedidiah J. ^[1]; Kakkireni, Saketh ^[1]; Gélinas, Guillaume ^[2]; Garaffa, Jeremy F. ^[3]; Swain, Santosh K. ^[1]; Lynn, Kelvin G. ^[1]

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+ Show Author Affiliations

1. Washington State Univ., Pullman, WA (United States)
2. 5N Plus Inc., Montréal, QC (Canada); École Polytechnique de Montréal, QC (Canada)
3. 5N Plus Inc., Montréal, QC (Canada)

Publication Date:

Tue Feb 04 00:00:00 EST 2020

Research Org.:

Washington State Univ., Pullman, WA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1801120

Alternate Identifier(s):

OSTI ID: 1599666

Grant/Contract Number:  

NA0002565

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Crystal Growth

Additional Journal Information:

Journal Volume: 535; Journal ID: ISSN 0022-0248

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY