Self-organization in growth of quantum dot superlattices.
TL;DR: The growth of multilayer arrays of coherently strained islands self-organizes into a more regular three-dimensional arrangement, providing a possible route to obtain the size uniformity needed for electronic applications of quantum dot arrays.
Abstract: We investigate the growth of multilayer arrays of coherently strained islands, which may serve as ``quantum dots'' in electronic devices. A simple model reproduces the observed vertical correlation between islands in successive layers. However, the arrangement of islands is not simply repeated from layer to layer. Instead, the island size and spacing grow progressively more uniform. In effect, the structure ``self-organizes'' into a more regular three-dimensional arrangement, providing a possible route to obtain the size uniformity needed for electronic applications of quantum dot arrays.
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TL;DR: In this article, solution phase syntheses and size-selective separation methods to prepare semiconductor and metal nanocrystals, tunable in size from ∼1 to 20 nm and monodisperse to ≤ 5%, are presented.
Abstract: ▪ Abstract Solution phase syntheses and size-selective separation methods to prepare semiconductor and metal nanocrystals, tunable in size from ∼1 to 20 nm and monodisperse to ≤5%, are presented. Preparation of monodisperse samples enables systematic characterization of the structural, electronic, and optical properties of materials as they evolve from molecular to bulk in the nanometer size range. Sample uniformity makes it possible to manipulate nanocrystals into close-packed, glassy, and ordered nanocrystal assemblies (superlattices, colloidal crystals, supercrystals). Rigorous structural characterization is critical to understanding the electronic and optical properties of both nanocrystals and their assemblies. At inter-particle separations 5–100 A, dipole-dipole interactions lead to energy transfer between neighboring nanocrystals, and electronic tunneling between proximal nanocrystals gives rise to dark and photoconductivity. At separations <5 A, exchange interactions cause otherwise insulating ass...
4,116 citations
TL;DR: In this article, the authors reviewed the early stages of epitaxial growth and showed how the growth kinetics can be employed to create well-defined island morphologies and island arrays in a self-organization process.
851 citations
TL;DR: The atomic nature of the most important kinetic mechanisms of film growth is explored, which include adatom diffusion on terraces, along steps, and around island corners; nucleation and dynamics of the stable nucleus; atom attachment to and detachment from terraces and islands; and interlayer mass transport.
Abstract: Growth of thin films from atoms deposited from the gas phase is intrinsically a nonequilibrium phenomenon governed by a competition between kinetics and thermodynamics. Precise control of the growth and thus of the properties of deposited films becomes possible only after an understanding of this competition is achieved. Here, the atomic nature of the most important kinetic mechanisms of film growth is explored. These mechanisms include adatom diffusion on terraces, along steps, and around island corners; nucleation and dynamics of the stable nucleus; atom attachment to and detachment from terraces and islands; and interlayer mass transport. Ways to manipulate the growth kinetics in order to select a desired growth mode are briefly addressed.
814 citations
TL;DR: In this paper, the authors discuss the calculation of strain fields, which play an important role in the formation of such nanostructures and also influence their structural and optoelectronic properties.
Abstract: Instabilities in semiconductor heterostructure growth can be exploited for the self-organized formation of nanostructures, allowing for carrier confinement in all three spatial dimensions. Beside the description of various growth modes, the experimental characterization of structural properties, such as size and shape, chemical composition, and strain distribution is presented. The authors discuss the calculation of strain fields, which play an important role in the formation of such nanostructures and also influence their structural and optoelectronic properties. Several specific materials systems are surveyed together with important applications.
752 citations
TL;DR: In this article, the size-tunable silver nanoparticle arrays by nanosphere lithography and their structural characterization by atomic force microscopy (AFM) were used to determine the in-plane diameter and out-of-plane height of Ag nanoparticles.
Abstract: Nanosphere lithography (NSL) is an inexpensive, inherently parallel, high-throughput, and materials-general nanofabrication technique capable of producing well-ordered 2D periodic particle arrays of nanoparticles. This paper focuses on the synthesis of size-tunable silver nanoparticle arrays by nanosphere lithography and their structural characterization by atomic force microscopy (AFM). The in-plane diameter, a, of Ag nanoparticles was tuned from 21 to 126 nm by systematic variation of the nanosphere diameter, D. Similarly, the out-of-plane height, b, was tuned from 4 to 47 nm by varying the mass thickness, dm, of the Ag overlayer. Experimental measurements of a, b, and interparticle spacing dip of many individual nanoparticles as a function of D and dm were carried out using AFM. These studies show (i) b = dm, (ii) dip accurately corresponds to predictions based on the nanosphere mask geometry, (iii) a, after correction for AFM tip convolution, is governed only by the mask geometry and the standard devi...
747 citations