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On the Cover

On the Cover Image
A Renaissance in Atom-Probe Tomography. This issue of MRS Bulletin presents the basic physical concepts of atomprobe tomography (APT) and discusses its applications for analyzing material chemically for a wide range of materials on a subnano meter scale. The cover figure presents atom-probe tomographic results of the nickel monosilicide portion of a Ni0.95Pt0.05/Si thin film, which was rapid thermally annealed at 420°C for five seconds prior to the APT analyses. The results represent direct observation on an atomic scale, employing APT, of short-circuit diffusion of platinum atoms along two grain boundaries (GBs) in a thin nickel monosilicide film, which sits on the silicon(100) substrate. The top portion is a two-dimensional vertical slice along the analysis direction, [100], with the individual platinum, nickel, and silicon atoms in red, green, and blue, respectively. The graph, middle portion, is a plot of the nickel and platinum concentration profiles as a function of their lateral positions, which demonstrates an enhanced platinum concentration at the two GBs and a concomitant decrease in the nickel concentration, thereby proving that platinum atoms are substituting for nickel atoms in the GBs. The bottom portion of the cover consists of three horizontal two-dimensional slices through the nickel monosilicide film, with the platinum atoms clearly decorating the GBs. Employing these 5-nm-thick slices, it is demonstrated that there is not a platinum concentration gradient along the GBs; therefore, its diffusivity is significantly greater than the diffusivity of nickel in the grains. The images are printed courtesy of the American Institute of Physics and the Electrochemical Society. See the technical theme that begins on p. 717.
ALSO IN THIS ISSUE: Manipulation of Photons by Photonic Crystals. Shown on the cover is a schematic drawing and a scanning electron microscope image of a 3D photonic crystal that was developed to control spontaneous emission.