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Dr. Virginia M. Ayres
The Electronic and Biological Nanostructures Laboratory
Research - Nanoelectronics

NANOELECTRONICS: Internal and Electronic Structure(s) of Gallium Nitride Nanowires.

Our research group has contributed the first recognition, characterization and applications of multi-domain zinc-blende/wurtzite gallium nitride nanowires, and single-phase gallium nitride wurtzite nanowires that can accommodate a single nanopipe. The internal structures of gallium nitride (GaN) nanowires lead to unique electronic structures for device applications on one hand, and to increased depth of understanding of the ways in which nucleation, growth and relaxation mechanisms interplay differently in 1D as opposed to 3D condensed matter on the other. The latter leads to controlled growth of really unique structures and capabilities.

The images shown below are from the series of investigations during which we discovered the internal structures of GaN nanowires.

Our initial report provided evidence for GaN nanowires with zinc-blende and wurtzite domains that extended the full length of the nanowire (several microns). HRTEM, quantitative EELS and EDS, and cathodoluminescence (our thanks to co-author M. Petkov, JPL) were used to prove the existence of this previously unreported internal structure. Jacobs, BW, et al., Nano Letters, 2007.

A multi-domain internal structure is enabled by multiple totally coherent (111)/(0001) internal interfaces. This was proved through investigation of perpendicular HRTEM of nanowire cross-sections, fabricated by focused ion beam (FIB) methods. The zinc-blende growth orientation is [011] and the wurtzite growth orientation is . Jacobs, BW, et al., Nanotechnology, 2008.

First HRTEM showing ZincBlende and Wurtzite GaN nanowires. Jacobs, BW, et al., Nano Letters, 2007.

The multi-domain zinc-blende/wurtzite nanowires were grown by a vapor-solid mechanism at lower (850-950C ) furnace temperatures in a quartz tube furnace (by M. He, J.B. Halpern, Howard University). At a higher 1000C furnace temperature, the great majority of nanowires are single-phase wurtzite whose growth orientation changes from to [0001]. HRTEM of FIB cross-sections of nanowires and rods grown at the higher 1000C furnace temperature established the frequent presence of a second type of internal structure: a single nanopipe. This implies that a dislocation-driven growth mechanism may dominate GaN nanowire formation at higher temperatures. Jacobs, BW, et al., Nano Letters, 2008, Ayres, VM, et al, Int. J. Nanomanufac., 2009.

GaN Nanowire References

  1. Jacobs, BW, McElroy, K, Al-Duhaileb, RA, Crimp, MA, Stallcup, RE, Hartman, A, Tupta, MA, Ayres, VM. Cross-Section High Resolution Transmission Electron Microscopy and Nanoprobe Investigation of Gallium Nitride Nanowires. In press, Int.J. Nanomanufac. 2009.
  2. Jacobs, BW, Crimp, MA, McElroy, K, Ayres, VM (2008). Nanopipes in Gallium Nitride Nanowires and Rods. Nano Lett. 8: 4354-4358.
  3. Jacobs, BW, Ayres, VM, Crimp, MA, McElroy, K (2008). Internal Structure of Multiphase Zinc-Blende Wurtzite Gallium Nitride Nanowires. Nanotech. 19: 405706 (6 pp).
  4. Jacobs, BW, Ayres, VM, Petkov, MP, Halpern, JB, He, M, Baczewski, AD, McElroy, K, Crimp, MA, Zhang, J, Shaw, HC (2007). Electronic and Structural Characteristics of Zinc-Blende Wurtzite Biphasic Homostructure GaN Nanowires. Nano Lett. 7: 1435-1438.
  5. Jacobs, BW, Ayres, VM, Stallcup, RE, Hartman, A, Tupta, MA, Baczewski, AD, Crimp, MA, Halpern, JB, He, M Shaw, HC (2007). Electron Transport in Zinc-Blende Wurtzite Biphasic Gallium Nitride Nanowires and GaNFETs. Nanotech. 18: 475710 (6 pp).
  6. Rutledge, SL, Shaw, HC, Yowell, LL, Chen, Q, Jacobs, BW, Song, SP, Ayres, VM (2006). Self Assembly and Correlated Properties of Electrospun Carbon Nanofibers. Diamond Relat. Mater. 15: 1070-1074.
  7. Jacobs, BW, Ayres, VM, Tupta, MA, Stallcup, RE, Hartman, A, Halpern, JB, He, M, Crimp, MA, Baczewski, AD, Tram, NV, Chen, Q, Fan, Y, Kumar, S, Udpa, L (2006). Electronic Transport Characteristics of Gallium Nitride Nanowire-based Nanocircuits. 6th IEEE Conf. Nanotechnology Proc. 02: 496-499.
  8. Ayres, VM, Jacobs, BWSong, SP, Ronningen, RM, Zeller, AF, Crimp, MA, Halpern, JB, He, M, Petkov, MP, Liu, D, Shaw, HC (2005). Nanotube, Nanowire and Nanocircuit Behavior in Simulated Space Environments. SPIE Photonics for Space Environments X, Editor: Edward W. Taylor, SPIE, Bellingham, WA, 2005. Article CID No. 589702. Vol. 5897: 1-14.
  9. Shaw, HC, Liu, D, Jacobs, BW, Ayres, VM, Ronningen, RM, Zeller, AF, Crimp, MA, Halpern, JB, He, M, Harris, GL, Petkov, MP (2005). Performance of Nanomaterials and Actively Running Nanocircuits During Heavy Ion Irradiation. Proc. 12th NASA Symp.VLSI Design, Editor: G. Donohoe, Cour d'Alene, ID, October 2005.
  10. Jacobs, BW, Ayres, VM, Crimp, MA, Ronningen, RM, Zeller, AF, Shaw, HC, Kogut, AJ, Benavides, JB, Petkov, MP, Halpern, JB (2005). Investigation of Space Radiation Resiliency of Carbon Nanotube and Gallium Nitride Nanocircuits. Mater. Res. Soc. Symp. Proc.: Materials for Space Applications, Editors: Mircea Chipara, David L. Edwards, Roberto S. Benson, Shawn Phillips, The Materials Research Society, Warrendale, PA. Article NN6.8, Vol. 851: 287-292.
© Copyright 2011, Virginia M. Ayres