A numerical study has been carried out to optimize the zone refining process parameters such as zone length, zone travel rate, number of passes and the effect of molten zone stirring in ultra-high purification of gallium. Theoretical interpretation of the impurity concentration profile along the refined gallium ingot is also ascertained. Based upon the optimized parameters obtained through the study, 5N2 (99.9992% pure) gallium is subjected to zone refining for 50 passes and mechanically stirred at 20-35 rpm by a rotational mechanism in the directional freezing system. The refined gallium has a purity level of 7N2 (99.999992%) and the total impurity concentration is reduced to 77.7 ppb with respect to 24 impurities, as analyzed by glow discharge mass spectrometry (GDMS). The purified gallium is used as the starting material to grow GaAs epitaxial layers by liquid phase epitaxy technique. The quality of the grown layer is tested by secondary ion mass spectroscopy (SIMS), Hall measurements and low-temperature photocapacitance techniques. © 2009 Elsevier B.V. All rights reserved.

K GHOSH

V N MANI

S DHAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Crystal Growth

Glycerol–water mediated green synthesis of PbS quantum dots (QDs) is introduced utilizing distinctive precipitation strategies for bioimaging application.

Fulltext

RSC Advances

Glycerol–water mediated centrifuge controlled green synthesis of oleic acid capped PbS quantum dots for live cell imaging

An "experimental friendly" model for zone refining process is proposed which predicts effective zone length in each refining passes that would lead to maximal solute removal, thereby leading to ultrapurification of the material for use in high-end electronic applications. The effectiveness of the model is experimentally tested and validated by purifying gallium from 4N (99.99%) to 6N5 (99.99995%) purity level at 30% yield and ∼6 N at 70% yield with respect to targeted metallic impurities such as, Zn, Cu, Al, Ca, Bi, Si, Pb, Ni, Mn, and Fe, as analyzed by inductively coupled plasma optical emission spectrometry, graphite furnace atomic absorption spectrometry, and high resolution inductively coupled plasma mass spectrometry techniques. The distribution coefficient (k) of all the targeted impurities, detected in the purified gallium, was found to be less than 1. By comparing the experimentally obtained axial concentration profiles with the theoretical calculations, the k values of some detected impurities, such as Ca and Al, are determined to be ∼0.8, Pb and Bi to be 0.7, Cu to be 0.65, and Fe to be 0.68, which prove the efficiency of the proposed model in reducing the concentration of these vulnerable impurities significantly. Following the model and as evidenced from the theoretical predictions, degradation of material purification containing a mixture of impurities having k less than as well as greater than 1 was elucidated experimentally by zone refining of 4N6 indium. Only a 40% yield of 5N6 indium was obtained, thereby highlighting the intricacies and problem areas in ultrapurification of these types of material. © 2008 American Institute of Physics.

Journal of Applied Physics

A modeling approach for the purification of group III metals (Ga and In) by zone refining

Who's Who

Cole, Nathan James, (born 1980), Headmaster, Wilson’s School, Wallington, since 2014

Material Science Research India

Preparation of Pure Crystalline Indium and its Characterization

Reproduction, Fertility and Development

Identification of genes regulated by an interaction between v3 integrin and vitronectin in murine decidua

Separation and Purification Technology

A novel in-situ technique of ultra purification of cadmium for electronic applications

Numerical study and experimental investigation of zone refining in ultra-high purification of gallium and its use in the growth of GaAs epitaxial layers

Journal	Data powered by TypesetJournal of Crystal Growth
Publisher	Data powered by TypesetELSEVIER SCIENCE BV
ISSN	0022-0248