Observing the Precise Location of Atoms in Nitride Crystals
Progress in developing new materials and devices based on nanotechnology strongly depends on the availability of new techniques for “seeing” the structural details that determine their behavior. In a collaboration with IBM and NION, CNS researchers are working on the implementation of a novel aberration-corrected scanning transmission electron microscope with unsurpassed resolution of less then 0.1 nm, approximately 10 million times smaller then a human hair, and less than most atoms. The comet-like objects seen in this electron microscope image below are pairs of atomic columns, where the yellow dots are large Al atoms and the red tails are tiny N atoms. This image, taken at extreme spatial resolution limits (~0.08 nm), was obtained with the use of a prototype aberration-corrected scanning transmission electron microscope at the IBM T.J. Watson Research Center by Cornell scientists and Dr. P.E. Batson of IBM. The position of the nitrogen with respect to the aluminum determines important electrical properties of the crystal, but normally cannot be observed directly .
Ultra high resolution scanning transmission electron micrograph of an aluminum nitride crystal showing the individual atomic columns of aluminum (large yellow dots) and nitrogen atoms (red tail) on the right. The crystalline structure is shown schematically on the left with aluminum in red and nitrogen in blue.
[CNS Investigator: Silcox Group – Nanocharacterization Thrust, Center for Nanoscale Systems, Cornell University]
For additional information see:
- K. A. Mkhoyan, P. E. Batson, J. Cha, W. J. Schaff, J. Silcox, “Direct determination of Local Lattice Polarity”, Science 312, 1354 (2006)