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- Carlberg, Torbjörn
(författare)
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A Review of Radial Segregation in Crystal Growth during Microgravity
- 2006
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Ingår i: Progress in crystal growth and characterization of materials. - : Elsevier BV. - 0960-8974 .- 1878-4208. ; 52:3, s. 213-222
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Forskningsöversikt (refereegranskat)abstract
- This review describes radial segregation results from crystal growth experiments in microgravity, together with their corre-sponding theoretical treatments. The paper is structured in terms of the different factors influencing radial segregation during crystal growth, such as: curved growth interfaces, variations in boundary layer thicknesses, weak convection, facets and magnetic fields. In a number of experiments considerably stronger radial segregation occurs in space than is normally observed on earth. The theoretical treatments lead to a sound understanding of all of the results. Possible ways to avoid the problem, such as the application of magnetic fields, are outlined.
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- Dick Thelander, Kimberly
(författare)
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A review of nanowire growth promoted by alloys and non-alloying elements with emphasis on Au-assisted III-V nanowires
- 2008
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Ingår i: Progress in Crystal Growth and Characterization of Materials. - : Elsevier BV. - 0960-8974. ; 54:3-4, s. 138-173
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Forskningsöversikt (refereegranskat)abstract
- Seed particles of elements or compounds which may or may not form alloys are now used extensively in promoting well-controlled nanowire growth. The technology has evolved following the well-known Vapour-Liquid-Solid (VLS) model which was developed over 40 years ago. This model indicates that a liquid alloy is formed from the seed particle and the growth precursor(s), resulting in crystal growth by precipitation from a supersaturated solution. The enhanced growth rate compared to the bulk growth from the vapour is typically attributed to preferential decomposition of precursor materials at or near the particle surface. Recently, however, there has been much interest in further developing this model, which was developed for Au-assisted Si whiskers (with diameter on the micrometre scale), in order to generally describe particle-assisted growth on the nanoscale using a variety of materials and growth systems. This review discusses the current understanding of particle-assisted nanowire growth. The aim is first to give an overview of the historical development of the model, with a discussion of potential growth mechanisms. In particular, the enhancement of growth rate in one dimension due to preferential deposition at the particle-wire interface will be discussed. Then, the particular example of Ill-V nanowires grown by metal-organic vapour phase epitaxy using Au particles will be revised, with details of the various growth processes involved in this system. The aim of this review is not to provide a conclusive answer to the question of why nanowires grow from seed particle alloys, but to describe the progress made towards this goal of a unified theory of growth, and to clarify the current standing of the question. (c) 2008 Elsevier Ltd. All rights reserved.
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