Research‎ > ‎

Nanostructure Visualization

Personnel: Megan Hill, Chunyi Huang, Alex Chang
Collaborators: D. Seidman, G.T. Wang (Sandia National Lab), S. Hruszkewycz (Argonne National Lab)
Applications: conventional and novel semiconductor device technologies

The nanotechnology revolution is driven by advances in both materials and characterization. We have developed approaches to map the positions of individual atoms in three dimensions with atomic resolution, enabling structure-property relationships to be defined down to the ultimate length-scale of materials.

3D Atomic Composition Mapping

Intentional impurity atoms, or dopants, are used to control the electronic properties of semiconductors, but it is very challenging to determine the concentration and distribution of dopant atoms in extremely small structures such as nanowires. We pioneered the use of atom probe tomography to map the positions of dopant atoms in semiconductor nanowires (see also references below). This ability enables the quantitative correlation of electrical properties and the development of much needed models of nanowire doping (with Voorhees).

D. E. Perea, E. R. Hemesath, E. J. Schwalbach, J. L. Lensch-Falk, P. W. Voorhees, and L. J. Lauhon, "Direct Measurement of Dopant Distribution in an Individual Vapor-Liquid-Solid Nanowire" Nature Nanotechnology 4, 315-319 (2009).

3D Strain and Structure Mapping

Coherent X-ray imaging by nanofocused hard x-rays can be used to probe strain and other structural features in nanowires.  Scanning probe measurements by Bragg Projection Ptychography (BPP) have been used to image 3D strain in InGaAs nanowires. Further, BPP can be used to map stacking defects in nanowires with better than 2 nm resolution.

Hruszkewycz, S. O., et al. "Quantitative nanoscale imaging of lattice distortions in epitaxial semiconductor heterostructures using nanofocused X-ray Bragg projection ptychography." Nano letters 12.10 (2012): 5148-5154

Additional References