9508572 Cohen This research aims at a definitive assessment of doping and diffusion effects in organometallic vapor phase epitaxy (OMVPE) with the study of GaAs, InP, and InGaAs. The research emphasis is on atomicl level details of nucleation, epitaxy, and crystal dislocation formation. Studies will be conducted to better understand and hence to control: (1) suppression of diffusion in order to minimize junction motion, precipitation in heavily doped regions, misfit dislocation formation, and (2) enhancement of diffusion to produce second phase formation including adjacent phases with potential application for lateral devices with different bandgaps. Changes in diffusivity and dopant solubility will be related to Fermi level pinning and the orientation of the wafer surface. The results will be characterized in terms of mesoscopic defect structures such as bunching of atomic steps, nucleation or suppression of misfit dislocations, and second condensed phase formation. %%% This project will be important to gaining increased fundamental understanding of doping and diffusion related effects of compound semiconductor materials which occur during their synthesis and processing. An important feature of the program is the training of graduate and undergraduate students in a fundamentally and technologically significant area. The knowledge and understanding of materials, and materials processing resulting from this program is expected to contribute significantly to advanced devices used for information processing, computing, and telecommunications. ***
