Author : Solmaz Torabi
Publisher :
ISBN 13 : 9781124299013
Total Pages : 123 pages
Book Rating : 4.2/5 (99 download)
Book Synopsis Modeling and Simulations of Quantum Dots and Other Nanostructures by : Solmaz Torabi
Download or read book Modeling and Simulations of Quantum Dots and Other Nanostructures written by Solmaz Torabi and published by . This book was released on 2010 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: In microelectronic technology, there is a need to manufacture the next generation of smaller, faster, and efficient devices. However there are some fundamental that prevents making smaller devices. The use of self-assembly process to manufacture ordered semiconductor nanostructures such as quantum dots promises to be an inex- pensive and effective route to overcome size scale limitations in current fabrication processes. In crystalline films these nanostructures arise through instability originat- ing from a lattice misfit between film and substrate, from strong surface anisotropies or from kinetic surface fluxes. Producing such ordered nanostructure is still chal- lenging. A fundamental understanding of the self-assembly process during epitaxial growth is necessary to achieve controlled quantum scale structures. In this thesis, we study the influence of anisotropic surface and strain energies as well as continuous mass deposition on heteroepitaxial thin film growth by modeling means. There are different classical ways to model the anisotropic surface energy; however, they have mathematical and physical limitations. This motivated us to develop two new ways to model this energy. In the first method, the anisotropic surface energy multiplied to the isotropic CahnHilliard free energy. Our model contains a high-order Willmore regularization, where the square of the mean curvature is added to the energy, to remove the ill-posedness introduced by sharp corners. A key feature of this approach is the development of a new formulation in which the interface thickness is independent of crystallographic orientation. This makes the Willmore regularization compatible with the rest of the energy. Both numerically and analytically, we show the convergence of our phase field model to the general sharp interface model. In the second method, we develop an extended Cahn-Hilliard model. Incorporating high order terms in the energy, crystalline symmetries can be modeled naturally. For example to simulate Silicon, the diamond cubic symmetry is needed. Accordingly, terms involving 4th order derivatives are included in the energy. One advantage of this approach is its intrinsic regularized behavior. For this system, we develop an energy-stable scheme in which the energy decreases for any time step.
