title: Barrierless Switching between a Liquid and Superheated Solid Catalyst during Nanowire Growth.
abstract: Knowledge of nucleation and growth mechanisms is essential for the synthesis of nanomaterials, such as semiconductor nanowires, with shapes and compositions precisely engineered for technological applications. Nanowires are conventionally grown by the seemingly well-understood vapor-liquid-solid mechanism, which uses a liquid alloy as the catalyst for growth. However, we show that it is possible to instantaneously and reversibly switch the phase of the catalyst between a liquid and superheated solid state under isothermal conditions above the eutectic temperature. The solid catalyst induces a vapor-solid-solid growth mechanism, which provides atomic-level control of dopant atoms in the nanowire. The switching effect cannot be predicted from equilibrium phase diagrams but can be explained by the dominant role of the catalyst surface in modulating the kinetics and thermodynamics of phase behavior. The effect should be general to metal-catalyzed nanowire growth and highlights the unexpected yet technologically relevant nonequilibrium effects that can emerge in the growth of nanoscale systems.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Pinion
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Hill
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Christesen
authors.affiliation: Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University , Nashville, Tennessee 37235, United States.
authors.forename: James R
authors.initials: JR
authors.lastname: McBride
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: James F
authors.initials: JF
authors.lastname: Cahoon