Vapor‐liquid‐solid mechanism of single crystal growth
About: This article is published in Applied Physics Letters.The article was published on 1964-03-01. It has received 6579 citations till now. The article focuses on the topics: Vapor–liquid–solid method & Seed crystal.
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TL;DR: The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures, which could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides.
Abstract: Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section with typical widths of 30 to 300 nanometers, width-to-thickness ratios of 5 to 10, and lengths of up to a few millimeters. The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and building functional devices along individual nanobelts.
5,677 citations
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TL;DR: Studies carried out with different conditions and catalyst materials confirmed the central details of the growth mechanism and suggest that well-established phase diagrams can be used to predict rationally catalyst materials and growth conditions for the preparation of nanowires.
Abstract: A method combining laser ablation cluster formation and vapor-liquid-solid (VLS) growth was developed for the synthesis of semiconductor nanowires. In this process, laser ablation was used to prepare nanometer-diameter catalyst clusters that define the size of wires produced by VLS growth. This approach was used to prepare bulk quantities of uniform single-crystal silicon and germanium nanowires with diameters of 6 to 20 and 3 to 9 nanometers, respectively, and lengths ranging from 1 to 30 micrometers. Studies carried out with different conditions and catalyst materials confirmed the central details of the growth mechanism and suggest that well-established phase diagrams can be used to predict rationally catalyst materials and growth conditions for the preparation of nanowires.
4,405 citations
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TL;DR: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each that are among the hottest research topics of the last decades.
Abstract: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each. Their size ranges from 2-3 to about 20 nm. What is special about this size regime that placed NCs among the hottest research topics of the last decades? The quantum mechanical coupling * To whom correspondence should be addressed. E-mail: dvtalapin@uchicago.edu. † The University of Chicago. ‡ Argonne National Lab. Chem. Rev. 2010, 110, 389–458 389
3,720 citations
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TL;DR: In this paper, a review of various nanostructures of ZnO grown by the solid-vapour phase technique and their corresponding growth mechanisms is presented. And the application of nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.
Abstract: Zinc oxide is a unique material that exhibits semiconducting and piezoelectric dual properties. Using a solid–vapour phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by the solid–vapour phase technique and their corresponding growth mechanisms. The application of ZnO nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.
3,361 citations
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TL;DR: In this article, the authors discuss the development of a general approach to rational synthesis of crystalline nanowires of arbitrary composition, and illustrate solutions to these challenges with measurements of the atomic structure and electronic properties of carbon nanotubes.
Abstract: Dimensionality plays a critical role in determining the properties of materials due to, for example, the different ways that electrons interact in three-dimensional, twodimensional (2D), and one-dimensional (1D) structures.1-5 The study of dimensionality has a long history in chemistry and physics, although this has been primarily with the prefix “quasi” added to the description of materials; that is, quasi-1D solids, including square-planar platinum chain and metal trichalcogenide compounds,2,6 and quasi2D layered solids, such as metal dichalcogenides and copper oxide superconductors.3-5,7,8 The anisotropy inherent in quasi-1D and -2D systems is central to the unique properties and phases that these materials exhibit, although the small but finite interactions between 1D chains or 2D layers in bulk materials have made it difficult to address the interesting properties expected for the pure low-dimensional systems. Are pure low-dimensional systems interesting and worth pursuing? We believe that the answer to this question is an unqualified yes from the standpoints of both fundamental science and technology. One needs to look no further than past studies of the 2D electron gas in semiconductor heterostructures, which have produced remarkably rich and often unexpected results,9,10 and electron tunneling through 0D quantum dots, which have led to the concepts of the artificial atom and the creation of single electron transistors.11-15 In these cases, lowdimensional systems were realized by creating discrete 2D and 0D nanostructures. 1D nanostructures, such as nanowires and nanotubes, are expected to be at least as interesting and important as 2D and 0D systems.16,17 1D systems are the smallest dimension structures that can be used for efficient transport of electrons and optical excitations, and are thus expected to be critical to the function and integration of nanoscale devices. However, little is known about the nature of, for example, localization that could preclude transport through 1D systems. In addition, 1D systems should exhibit density of states singularities, can have energetically discrete molecularlike states extending over large linear distances, and may show more exotic phenomena, such as the spin-charge separation predicted for a Luttinger liquid.1,2 There are also many applications where 1D nanostructures could be exploited, including nanoelectronics, superstrong and tough composites, functional nanostructured materials, and novel probe microscopy tips.16-29 To address these fascinating fundamental scientific issues and potential applications requires answers to two questions at the heart of condensed matter chemistry and physics research: (1) How can atoms or other building blocks be rationally assembled into structures with nanometer-sized diameters but much longer lengths? (2) What are the intrinsic properties of these quantum wires and how do these properties depend, for example, on diameter and structure? Below we describe investigations from our laboratory directed toward these two general questions. The organization of this Account is as follows. In section II, we discuss the development of a general approach to the rational synthesis of crystalline nanowires of arbitrary composition. In section III, we outline key challenges to probing the intrinsic properties of 1D systems and illustrate solutions to these challenges with measurements of the atomic structure and electronic properties of carbon nanotubes. Last, we discuss future directions and challenges in section IV.
3,218 citations
References
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TL;DR: In fact, the existence of a critical finite supersaturation for further growth has only been established for a few materials, and then for individual faces of individual crystals, being different from case to case as discussed by the authors.
Abstract: The kinetic theory of the nucleation of new phases, developed especially by Volmer,l by Farkas,2 by Kaischew and Stranski3 and by Becker and DOring4 indicates that under typical conditions * the self-nucleation from vapour of new crystals, new liquid drops and fresh two-dimensional monolayers of molecules on a “ saturated ” crystal face require respectively supersaturations of the vapour by factors of typically 10, 5 and 1.5 respectively in order to proceed at appreciable rates. Experimentally, the first two of these figures are apparently correct : but the third is much larger than the actual supersaturation required to cause further growth of a crystal already formed. In fact, the existence of a critical finite supersaturation for further growth has only been established for a few materials, and then for individual faces of individual crystals, being different from case to case ; at the most it is about I yo. Volmer and S c h ~ l t z e , ~ who found a critical supersaturation of 0.8 yo for the growth of an iodine crystal from the vapour, interpreted this as the critical supersaturation for two-dimensional nucleation : but the quantitative discrepancy is far too great (for details of the growth rate formulzJ see the contributions of Burton and Cabrera to this Discussion). However, this discrepancy is not in the least surprising. One ought not to expect that any visible crystal will exhibit a completed perfect face needing fresh two-dimensional nucleation in order to grow. Investigation of the mechanical properties of solids shows that no macroscopic specimen ever exhibits the theoretical strength of the perfect crystal; and this enormous discrepancy (a factor of 100, say, and more for “good”
888 citations
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TL;DR: In this article, the basic chemistry and reaction kinetics pertinent to the growth of these films are discussed in detail in detail, including the hydrogen reduction of silicon tetrachloride appropriately doped with or.
Abstract: Epitaxial films of silicon with controlled thickness and resistivity either n‐ or p‐type may be grown using the hydrogen reduction of silicon tetrachloride appropriately doped with or . The basic chemistry and reaction kinetics pertinent to the growth of these films are discussed in detail in this paper.
135 citations
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TL;DR: In this article, small euhedral crystals of α-Al2O3 (sapphire) were observed following oxidation of aluminum and an aluminum alloy in wet hydrogen at high temperatures.
Abstract: Examination of small euhedral crystals of α‐Al2O3 (sapphire) that were observed following oxidation of aluminum and an aluminum alloy in wet hydrogen at high temperatures showed that growth probably occurs by decomposition of AlO on an Al2O3 surface. Rapid growth occurs on the tips of needles and the edges of platelets at lattice steps formed by intersection of hollow screw dislocations with these surfaces. Screw dislocations were detected by x‐ray measurement of the lattice twist they produce in the needle‐like crystals or ``whiskers.'' Needles were bent to elastic strains of over 2% corresponding to a strength of 1011 dyne cm−2.
90 citations
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46 citations