Simulation Tools for Strain Engineering, Manufacturing and Design of Novel Optical and Electronic Superlattice Materials and Surfaces

The overall objective of this Phase I proposal is to create a model based on molecular dynamics (MD) that can predict the specific Quantum Dot Superlattice (QDSL) heteroepitaxial structures that will grow, given various factors such as growth temperature, flux rate, and spacer thickness. AlGaN/GaN heterostructures have attracted a great deal of theoretical and experimental interest because of their applications in high-power microwave devices, in high-frequency field effect transistors and in blue light-emitting diodes, among others. Specifically, ab-initio density functional theory calculations will be performed to determine accurate parameters for the interatomic potentials to be employed in MD growth simulations. Next, potentials such as the Rockett and modified Stillinger-Weber potentials will be investigated for their suitability. Once the potential parameters have been optimized, MD simulations of the growth of InGaN/GaN QDSL heterostructures will be performed. After the simulated growth of each InGaN/GaN QDSL layer, the system will be allowed to equilibrate. Defect formation will be studied as the growth proceeds. The strain in these simulated structures will be calculated. The effect of strain on the electronic structure of InGaN/GaN QDSL structures will also be calculated. Finally, the tradeoffs in the choice of growth parameters will be explored.