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Three-dimensional (3D) mesostructured semiconductors show promising properties and applications

"Atomic gold–enabled three-dimensional lithography
for silicon mesostructures"

Zhiqiang Luo, Yuanwen Jiang, Benjamin D. Myers, Dieter Isheim,
Jinsong Wu, John F. Zimmerman, Zongan Wang, Qianqian Li,
Yucai Wang, Xinqi Chen, Vinayak P. Dravid, David N. Seidman, Bozhi Tian

Science 26 June 2015: Vol. 348 no. 6242 pp. 1451-1455 

NUANCE Center instrumentation was used both for mounting nanowires for
TEM and LEAP analysis (FEI Helios Nanolab) and TEM tomography (Hitachi HD-2300).



Above image was produced using the NUANCE Center's SEM and TEM.


Three-dimensional (3D) mesostructured semiconductors show promising properties and applications; however, to date, few methods exist to synthesize or fabricate such materials. Metal can diffuse along semiconductor surfaces, and even trace amounts can change the surface behavior. We exploited the phenomena for 3D mesoscale lithography, by showing one example where iterated deposition-diffusion-incorporation of gold over silicon nanowires forms etchant-resistant patterns. This process is facet-selective, producing mesostructured silicon spicules with skeletonlike morphology, 3D tectonic motifs, and reduced symmetries. Atom-probe tomography, coupled with other quantitative measurements, indicates the existence and the role of individual gold atoms in forming 3D lithographic resists. Compared to other more uniform silicon structures, the anisotropic spicule requires greater force for detachment from collagen hydrogels, suggesting enhanced interfacial interactions at the mesoscale.