Nano 'pin art': NIST arrays are step toward mass production of nanowires

Jul 30, 2010
This is a colorized micrograph of semiconductor nanowires grown at NIST in a precisely controlled array of sizes and locations. Credit: K. Bertness, NIST

NIST researchers grow nanowires made of semiconductors -- gallium nitride alloys -- by depositing atoms layer-by-layer on a silicon crystal under high vacuum. NIST has the unusual capability to produce these nanowires without using metal catalysts, thereby enhancing luminescence and reducing defects. NIST nanowires also have excellent mechanical quality factors.

The latest experiments, described in , maintained the purity and defect-free of NIST nanowires while controlling diameter and placement better than has been reported by other groups for catalyst-based nanowires. Precise control of diameter and placement is essential before nanowires can be widely used.

The key trick in the NIST technique is to grow the wires through precisely defined holes in a stencil-like mask covering the silicon wafer. The NIST nanowires were grown through openings in patterned masks. About 30,000 nanowires were grown per 76-millimeter-wide wafer. The technique controlled nanowire location almost perfectly. Wires grew uniformly through most openings and were absent on most of the mask surface.

Mask openings ranged from 300 to 1000 (nm) wide, in increments of 100 nm. In each opening of 300 nm or 400 nm, a single nanowire grew, with a well-formed hexagonal shape and a symmetrical tip with six facets. Larger openings produced more variable results. Openings of 400 nm to 900 nm yielded single-crystal nanowires with multifaceted tops. Structures grown in 1,000-nm openings appeared to be multiple wires stuck together. All nanowires grew to about 1,000 nm tall over three days.

NIST researchers analyzed micrographs to verify the uniformity of nanowire shape and size statistically. The analysis revealed nearly uniform areas of wires of the same diameter as well as nearly perfect hexagonal shapes.

Growing nanowires on silicon is one approach NIST researchers are exploring for making "nanowires on a chip" devices. Although the growth temperatures are too high—over 800 degrees Celsius—for silicon circuitry to tolerate, there may be ways to grow the nanowires first and then protect them during circuitry fabrication, lead author Kris Bertness says. The research was partially supported by the Defense Advanced Research Projects Agency (DARPA) Center on NanoscaleScience and Technology for Integrated Micro/Nano-Electromechanical Transducers (iMINT) at the University of Colorado at Boulder.

Explore further: Researchers make nanostructured carbon using the waste product sawdust

More information: K. A. Bertness, A. W. Sanders, D. M. Rourke, T. E. Harvey, A. Roshko, J.B. Schlager and N. A. Sanford. Controlled nucleation of GaN nanowires grown with molecular beam epitaxy. Advanced Functional Materials. Published online: July 13, 2010. DOI: 10.1002/adfm.201000381

Related Stories

Self-organized, one-dimensional Pt nanowires on Ge(001)

May 19, 2004

Oguzhan Gurlu and a group of scientists from University of Twente, Netherlands report about formation of Pt nanowires on Ge (001). Pt atoms adsorbed onto Ge(001) surface form extremely well-ordered nanowire arrays ...

Chemists measure copper levels in zinc oxide nanowires

Feb 19, 2008

Chemists at the National Institute of Standards and Technology have been the first to measure significant amounts of copper incorporated into zinc oxide (ZnO) nanowires during fabrication. The issue is important ...

Low-Temperature Growth and Properties of ZnO Nanowires

Jun 01, 2004

Xuan Wang et al. from Peking University, China report in the last issue of Applied Physics Letters about ZnO nanowires grown through evaporation of zinc powders under a low temperature of 400 C. Being about 10 ...

Recommended for you

Nanoparticle technology triples the production of biogas

Oct 22, 2014

Researchers of the Catalan Institute of Nanoscience and Nanotechnology (ICN2), a Severo Ochoa Centre of Excellence, and the Universitat Autònoma de Barcelona (UAB) have developed the new BiogàsPlus, a technology which allows ...

Research unlocks potential of super-compound

Oct 22, 2014

Researchers at The University of Western Australia's have discovered that nano-sized fragments of graphene - sheets of pure carbon - can speed up the rate of chemical reactions.

User comments : 0