This work involves AB intitio simulation studies for semiconductor materials processing. The project will provide the most careful test to date of the ability of approximate ab intitio tight binding models to predict the processing conditions necessary to produce desired materials properties. In particular, the PI's will study promising new dopants like Ga and In (to replace boron as a p-dopant) for semiconductor materials like Si and SiGe. This will involve a combination of simulation techniques (molecular statics, Molecular Dynamics and Kinetic Monte Carlo) to produce dopant diffusion profiles. The tight binding results for energies of formation and mobility of dopant species will be used in a continuum code to leverage the atomic-scale results to macroscopic scale properties. They will also investigate the role of stress, say at an SiGe/Si interface, to enhance lateral diffusion in a semiconductor device. The studies here, computer simulation of dopant diffusion in Si-rich materials, are crucial to the semiconductor industry aiming for sub-100nm device features in the 21st century. Close collaboration with local experimentalists and nearby industries will allow planning and execution of complementary experimental studies of these simulations.