IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Wednesday Sessions
       Session TF-WeA

Paper TF-WeA9
Connecting the Evolution and Coalescence of 3-dimensional Grain Structures to Reactor-scale Phenomena

Wednesday, October 31, 2001, 4:40 pm, Room 123

Session: Nucleation and Growth
Presenter: M.O. Bloomfield, Rensselaer Polytechnic Institute
Authors: M.O. Bloomfield, Rensselaer Polytechnic Institute
D.F. Richards, Rensselaer Polytechnic Institute
O. Klaas, Rensselaer Polytechnic Institute
J. Lu, Rensselaer Polytechnic Institute
A.M. Maniatty, Rensselaer Polytechnic Institute
M.S. Shepard, Rensselaer Polytechnic Institute
T.S. Cale, Rensselaer Polytechnic Institute
Correspondent: Click to Email
We have created a finite-element based, multiple level-set code to model the evolution and coalescence of grains and atomic scale islands during thin film growth. Our software tool can simulate the evolution of N grains or atomic-scale proto-grains. Grain boundaries are represented implicitly by a set of N+1 scalar fields, phi@sub i@(r,t) expressed on an unstructured mesh, subject to the condition that phi@sub i@(r,t) = 0 for all r on the boundary of grain i at time t.@footnote 1@ By extracting the zero contour, we can recover the grain boundaries at any time. Because each grain is associated with its own scalar field, properties such as lattice orientation can be easily retained on a grain-by-grain basis. The evolution of each grain is computed separately using the usual level set equation. We use an explicit positive coefficient scheme for this evolution. Level sets representing different regions are then reconciled to bring the them into agreement. To address distortions in the scalar fields, we implement a "redistancing" algorithm that corrects these distortions. This step stabilizes the evolution, allowing for simulations that include the coalescense of proto-grains and islands into complex grain structures. Demonstrations of this code are presented, including applications within a multiscale framework. Reactor scale simulations of reactant transport are performed using an FEM code. Reactant data are passed to this scale from the grain scale in the form of boundary conditions. This allows us to establish concentration fields of reactant both on the scale of 0.1 m, and using local refinement, on the 0.1 mm scale. The reactor-scale simulation passes reactant data back down to a grain-scale level set simulation. This allows us to show the interaction of phenomena such as reactor-scale reactant depletion on the resulting grain structure. @FootnoteText@ @footnote 1@Osher, S. and Sethian, J.A., J. Comput. Phys. 79, 12 (1988).