Thin fi lms are rarely stable structures, but are instead kinetically frozen as a consequence of formation far from equilibrium. With few exceptions, the total free energy associated with the interfaces of a fi lm is reduced if the fi lm agglomerates to form islands. Therefore, when fi lms are heated so that atomic diffusion occurs, they often dewet to form arrays of islands. Dewetting can occur at temperatures well below the melting temperature of the fi lm, so that the material remains in the solid state throughout the process. The rate of dewetting is higher in thinner fi lms, so that the temperature at which dewetting occurs decreases with decreasing fi lm thickness. Solid-state dewetting has long been a critical problem in microelectronics processing and much effort has been made to fi nd ways of preventing it. [1][2][3] On the other hand, solid-state dewetting has also been purposely induced to produce catalysts for growth of carbon nanotubes and semiconductor nanowires and has been proposed as a route for formation of complex electrode structures, as in for example, solid-oxide fuel cells. [4][5][6] In this paper, we demonstrate a technique through which solidstate dewetting can be templated to produce complex patterns in a controlled and designed way.Solid-state dewetting must initiate either at a pre-existing edge of a fi lm or through formation of holes that create edges. The latter process is catalyzed by defects, such as grain boundary triple junctions in polycrystalline fi lms. [ 7 ] Edges around the holes retract via surface diffusion driven by gradients in local surface curvature and rims develop along the edges. [7][8][9][10] These rims can undergo Rayleigh-like instabilities to form complex irregular morphologies. [ 8 ] Continuous polycrystalline fi lms on fl at surfaces dewet to form structures constituted of particles with broad distributions of sizes and spacings. [ 9 ] However, it has recently been shown that dewetting of polycrystalline fi lms on surfaces with regular pit-like topographic features can lead to ordered arrays of near mono-disperse particles. [ 11 , 12 ] It has also been shown that pre-patterning of polycrystalline fi lms on fl at surfaces can infl uence the degree of order of the resulting particles, but still in only a probabilistic way. [ 13 ] As a consequence of their use in modern microelectronics technology, dewetting of single-crystal silicon fi lms on amorphous silicon dioxide underlayers has also been recently observed and characterized. [14][15][16][17] In this case, there is a natural ordering of the particles resulting from the surface-energy anisotropy and single-crystal nature of the fi lm.Here we report that dewetting of pre-patterned single-crystal fi lms can be used to controllably create a wide array of dewetted structures with greater complexity and smaller length scales than the original pattern. We have used single-crystal Ni fi lms grown on single-crystal MgO substrates as a model system. Ni fi lms with different crystallographic orientations, controlled ...

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Scaling graphene growth using an oven to heat large substrates becomes less energy efficient as system size is increased. We report a route to graphene synthesis in which radio frequency (RF) magnetic fields inductively heat metal foils, yielding graphene of quality comparable to or higher than that of current chemical vapor deposition techniques. RF induction heating allows for rapid temperature ramp up/down, with great potential for large scale and rapid manufacturing of graphene with much better energy efficiency. Back-gated field effect transistors on a SiO2/Si substrate showed carrier mobility up to ∼14 000 cm(2) V(-1) s(-1) measured under ambient conditions. Many advantages of RF heating are outlined, and some fundamental aspects of this approach are discussed.

We report studies of complex morphological evolution during solid-state dewetting of 120 nm thick single-crystal Ni(100) and Ni(110) thin films on MgO(100) and MgO(110) substrates. During dewetting, holes that form in the Ni films evolve to complex shapes that depend on the crystallographic orientation of the films and annealing ambient. We characterize the origins of hole, line, and particle morphologies that develop during the dewetting process, and identify a sequence of instabilities that control the morphological evolution. This study provides mechanistic insights for control of dewetting to produce specific ordered structures.