32. Seeing Atoms Individually
John Silcox
John Silcox, Applied and Engineering Physics, colleague K. Andre Mkhoyan, and research team developed techniques that let scientists see individual atoms within crystal molecules. This advance allows researchers to predict more accurately at every point the physical properties of a crystal. The researchers used a scanning transmission electron microscope (STEM) at IBM on samples of aluminum nitride, gallium nitride, and other crystals important to nanotechnology research to demonstrate their technique. On a sample of aluminum nitride, the researchers used a technique called annular dark imaging, which revealed pear-shaped molecular columns, with the larger aluminum atoms at the thicker end and the smaller nitrogen atoms at the narrower end. This was the first time the smaller atoms in such a structure were caught in an image. The key is the narrowness of the scanning electron beam. This new technique allows researchers to characterize a crystal precisely at any region of the structure, which is key in nanotechnology, where the structure of an individual molecule can determine a device’s behavior.