Conclusions and Recommendations

In this project, we present a three-dimensional finite element scheme to simulate the growth process of quantum dots under both surface diffusion and interface migration. Results include the nucleation process of QD from rough surface, growth process in the early stage and also coarsening process. The fourth-order Runge-Kutta method is used to improve the numerical stability. Besides, the normalization of the governing equation also provides a tool to study the effect of each free energy contributor.

Future works:
1. Consideration of anisotropic surface energy(3D) would lead to formation of Pyramid-like QDs.
 
(http://www.hlphys.jku.at/groupsites/iv-vi/gallery/iv-vi_gallery.htm)



2. Consideration of wetting potential would lead to a wetting layer at the initial stage of QD growth. [7]

Furthermore, it is also possible to design a pair of material which have nonwetting interaction so that the deposited material could dewet the substrate. This process could possibly cut the diffusion process between neighbor islands, and stop the coarsening process at the late stage of quantum dot growth. The dewetting process is an effective approach to control the size of QDs.[8]
 


3. Pre-patterned substrate/multi-layered growth mode could be interesting because the long-range order/positioning of the QDs are still major issues for further application and commercialization.

http://cqd.eecs.northwestern.edu/research/qdots.php



4. Our codes could only handle the small perturbation on the surface, because the large interface movement requires update the Abaqus code to refine the meshing in thickness.


5. We employ a CST (constant triangle element) as the element in this project. It could be better to use a higher order element such as quadratic rectangular element to improve the accuracy of the simulation.