"ALGORITHMS: Microscope exposes atoms' inner mysteries"

A spherical-aberration corrector has enabled the transmission electron microscope at IBM's T.J. Watson Research Center (Yorktown Heights, N.Y.) to make the highest-resolution images in the world. Instead of blurry pictures of individual atoms, the researchers have obtained clear images of the individual molecular bonds among the different types of atoms in the crystalline lattice of a semiconductor surface. IBM recently installed a second-generation spherical-aberration correction system made by Nion Co. (Kirkland, Wash.) As a result, the world's highest-resolution images are now made on IBM's 120,000-electron-volt (eV) scanning-tunneling electron microscope (STEM). The researchers clearly imaged a crystalline aluminum nitride surface, showing the hexagonal "wurtzite" arrangement of atoms. The crystalline aluminum nitride layer was fabricated to experiment with storing charge in aluminum-nitride/gallium-nitride/aluminum-nitride quantum wells. The gallium nitride behaves as a semiconductor, storing as little as one charge carrier, while the aluminum-nitride sandwich insulates the quantum well from electrodes above and below it. The images clearly revealed for the first time the location and orientation of both the aluminum and the much tinier nitrogen atoms in the hexagonal wurtzite crystalline lattice pattern.
Text: http://www.eetimes.com/showArticle.jhtml?articleID=189602005