Nanometallicity in Si-based Amorphous Thin Films

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AbstractTechnical: This project aims for the discovery of new random materials that exhibit metal-insulator transitions when the sample size is comparable to electron's localization length. Such materials, recently observed in perovskite solid solutions and in SiO2 atomically dispersed with Pt, may find potential applications for resistance switching in non-volatile memory. These materials are solid solutions of an insulator and a metallic component. By varying the composition and the thickness of the thin films, we will engineer a tunable metal-insulator transition of the Anderson variety, being insulating at larger thickness, but metallic at smaller thickness. The transition can also be triggered by a voltage due to charge injection/removal, which alters the localization length. Local atomic structures and metallicity will be determined using synchrotron radiation, electron energy loss spectroscopy, and optical spectroscopy, whereas long range metallicity and transitions will be established using transport/dielectric measurements and atomistic simulations. Integrated research and educational activity built around PhD education, laboratory experience and remote laboratory access will benefit local and distant undergraduate and graduate students, as well as high school and university teachers.Nontechnical: The project explores fundamental material research at the nanoscale level where the prediction of quantum physics can be directly applied to material design with a potentially high payoff. The research is motivated by the insatiable need for new memory materials with a smaller footprint and a faster speed, to be used in computers and especially hand-held digital devices. Unlike conventional approaches that focus on materials of ever increasing perfection and purity, such as silicon single crystal, this project turns to random materials with a high concentration of impurities. If the project is successful, it will open a new avenue of technological opportunities. An education plan is integrated with the research: it emphasizes integration of instruction learning and laboratory learning, for both local and distant undergraduate and graduate students who, via on-line access, will gain laboratory experience.