Growth and Characterization of Rare-Earth Silicide Nanowires and Nanostructures

Self-assembled nanowires are potential structures for interconnects in nanoscale electronic applications. In this study, GdSi2, DySi2, and ScDy2 nanostructures are being grown on Si(100) substrates by evaporation/self assembly. Bulk coverages ranging from 0.3 to 3.0 monolayers of silicide result in a variety of morphologies and crystal structures. Large aspect ratio nanowires grow have been found to grow in <110>Si directions. Larger rectangular 3-D islands are also observed. The relationships between substrates, growth conditions, and nanostructure morphology and crystal structure are being characterized using scanning tunneling microscopy and advanced transmission electron microscopy techniques including HRTEM, convergent beam electron diffraction, and EELS.

Imaging of Dislocations in Bulk SEM Samples

The deformation and fracture behavior of materials is being studied by examining near surface dislocations in bulk SEM samples using electron channeling contrast imaging (ECCI). This novel approach facilitates in-situ deformation studies under well defined stress states, while avoiding the complications associated with TEM thin films. Currently, dislocation are being imaged in intermetallic alloy in an effort to optimize deformation behavior. Dislocations processes at both crack tips and at grain boundaries are being studied.

Radiation Effects on the Structure and Electronic Properties of Carbon Nanotubes

Traditional Si based electrons are susceptible to rapid degradation in space radiation environments, limiting their application in satellite and space exploration systems. Currently, carbon nanotubes are being developed for nanoscale electronic circuits. In this program, we are studying the stability of carbon nanotubes and nanotubes/metal contacts when exposed to high energy radiation. These structures are being irradiated with high energy (12,000 MeV) 86Kr ions, which simulate space radiation environments, in the National Superconducting Cyclotron Laboratory at Michigan State University. The irradiated structures are being characterized using high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) in order to determine the structural and electronic degradation as a function of exposure.

Reviewed Journal Publications

Bieler, T.R.; Fallahi, A.; Ng, B.C.; Kumar, D. Crimp, M.A.; Zamiri, A.; Pourboghrat, F.; Mason, D."Fracture Initiation/Propagation Parameters for Duplex TiAl Grain Boundaries Based on Twinning, Slip, Crystal Orientation, and Boundary Misorientation", Intermetallics, 13(9), 979-984, (2005).

Lan, Y.C.; Chen, X.L.; Crimp, M.A.; Cao, Y.G. ; Xu, Y.P.; Xu, T.; Lu, K.Q. "Single Crystal Growth of Gallium Nitride in Supercritical Ammonia," Phys. Stat. Sol. C, 2(7), 2066-2069, (2005).

Loloee, R.; Surazhdin, S.; Pratt, Jr., W.P.; Geng, H.; Crimp, M.A. "Magnetic Anisotropy and Structure of Epitaxial Permalloy Films Sputter Deposited on Nb(110)", Appl. Physic. Lett., 84 (13) 2364-2266 (2004).

Song, S.P.; Crimp, M.A.; Ayres, V.M.; Collard, C.; Holloway, J.; Terry, F.; Brake, M. "Formation of Hetro Silicon-Carbon Nanostructures by Growth/Etching", J. Nanoscience and Nanotechnology, 4 (7) 817-823 (2004).

Crimp, M.A.; Hile, J.T.; Bieler, T.R.; Glavicic, M.G. "Dislocation Density Measurements in Commercially Pure Titanium using Electron Channeling Contrast Imaging", in TMS Letters 1(1), 15-16, (2004).

Fallahi, A.; Kumar, D.; Zamiri, A.; Bieler, T.R.; Crimp, M.A.; Pourboghrat, F.; Mason, D.E. "The Effect of Grain Boundary Misorientation, Inclination, Crystal Orientation, and Stress State on Microcrack Initiation in Duplex TiAl Grain Boundaries", TMS Letters 1(5), 101-2, (2004).

Ng, B.C.; Simkin, B.A.; Crimp, M.A.; Bieler, T.R. "The Role of Mechanical Twinning on Microcrack Nucleation and Crack Propagation in a Near-<span class="symbol">g</span> TiAl Alloy", Intermetallics 12(12), 1317-1323, (2004).

Simkin, B.A.; Crimp, M.A.; Bieler, T.R.; Mason, D.E. "Method to index true orientation of TiAl from SACP patterns," Intermetallics 11(3), 215-23, (2003).

Zeng, L; Crimp, M. A.; Case, E. D. "The Interfacial Microstructure of Joined Single Crystal and Polycrystalline Alumina," Materials Science and Engineering A360, 228-236, (2003).

Simkin, B.A.; Crimp, M.A.; Bieler, T.R. "A Factor to Predict Microcrack Nucleation at Grain Boundaries," Scripta Met. et Mat. 49(2), 149-154, (2003).

Simkin, B.A.; Ng, B.C.; Bieler, T.R.; Crimp, M.A.; Mason, D.E. "Orientation Determination and Defect Analysis in the Near-Cubic Intermetallic-TiAl Using SACP," Intermetallics 11(3), 215-223, (2003).

Conference Proceedings

Jacobs, B.W.; Ayres, V. M.; Crimp, M.A.; Ronningen, R. M.; Zeller, A. F.; Shaw, H. C.; Kogut, A. J.; Benavides, J. B.; Petkov, M. P.; Halpern, J. B. "Investigation of Space Radiation Resiliency of Carbon Nanotube and Gallium Nitride Nanocircuits," in Materials for Space Applications; Chipara, M.; Edwards, D.L.; Benson, R.S., Shawn Phillips MRS Proc. 851, 287-292, (2005).

Ng, B.C.; Bieler, T.R.; Crimp, M.A.; Mason, D.E. "Prediction of crack paths based upon detailed microstructure characterization in a near-g TiAl Alloy," TMS MS&T 2004 Symposium on Materials Damage Prognosis; Larsen, J.M; Calcaterra, J.R.; Christodoulou, L.; Dent, M.L.; Hardman, W.J.; Jones, J.W.; Russ, S.M., eds., TMS (The Minerals, Metals & Materials Society), 307-314, (2005).

Jacobs, B.W.; Ayres, V. M.; Crimp, M.A.; Ronningen, R. M.; Zeller, A. F.; Shaw, H. C.; Kogut, A. J.; Benavides, J. B.; Petkov, M. P.; Halpern, J. B. "Investigation of Space Radiation Resiliency of Carbon Nanotube and Gallium Nitride Nanocircuits," in Materials for Space Applications, edited by M. Chipara, D. L. Edwards, R. S. Benson, Shawn Phillips MRS Proc., 851, 287-292, (2005).

Ng, B.C.; Crimp, M.A; Bieler, T.R.; Mason, D.E. "Studies of twin activity at crack tips in near-gamma TiAl using electron channeling contrast imaging", Gamma Titanium Aluminides 2003, ed. Y.W. Kim, H. Clemens, and A.H. Rosenberger, TMS, Warrendale, PA, 503-508, 2004.

Crimp, M.A.; Ng, B.C.; Simkin, B.A.; Bieler, T.R. "Microcrack Nucleation and Crack Propagation in <span class="symbol">g</span> TiAl," Defect Properties and Related Phenomena in Intermetallic Alloys, E.P. George, M.J. Mills, H. Inui, and G. Eggeler eds, MRS Proceedings 753, 143-148, (2003).

Crimp, M.A.; Simkin, B.A.; Ng, B.C.; Mason, D.E.; Bieler, T.R. "Microscale Characterization of Deformation Defects in Bulk Intermetallic Alloys using Electron Channeling Contrast Imaging," Proc. THERMAC 2003

Crimp, M.A. "Examination of Deformation Defects in Bulk Crystals using Electron Channeling Contrast Imaging," Electron Microscopy: Its Role in Materials Science, J.R. Weertman, K.T. Faber, M.E. Fine, P.E. Liaw, and B. Mori eds., TMS Proceedings, Warrendale PA, 3-11, (2003).

Crimp, M.A. "Study of the Micromechansims of Plasticity and Fracture in Bulk Metallic Samples using Electron Channeling Contrast Imaging," Proceedings of the Naval Steels Principal Officers Meeting, (published by the ONR on CD-ROM),(2003).

Song, S.P.; Jacobs, B.; Ayres, V.M. Crimp, M.A., Ronningen, R.; Zeller, A.; Shaw, H.; Benevides, J.J.; Liebforth M.; Plante, J. "Fundamental Space Radiation Interactions in New Nanoscale Materials," IEEE Conference Record of the 30th International Conference on Plasma Science, June 2-5, Jeju, Korea, p. 266, (2003).

Crimp, M.A.; Bieler, T.R.; Mason, D.E.; Simkin, B.A.; Ng,B.C. "Deformation transfer at Gamma-Gamma Boundaries in TiAl: Experimental Characterization and Modeling," Proceedings of the US-Korea Workshop on Advances in Metallic Structural Materials, (published by the AFOSR on CD-ROM), (2003).

Bieler, T.R.; Crimp, M.A.; Mason, D.E. "Mesoscopic Measurement and Modeling of Slip Transfer Across Boundaries in Anisotropic Metallic Systems," Proceedings of the 2003 AFOSR Contractors Meeting on Metals, (Published by the AFOSR in CD-ROM), (2003).

Other Works

Bieler, T.R.; Ng, B.C.; Telang, A.U.; Crimp, M.A. "Application of OIM to Study Heterogeneous Deformation in the Vicinity of Grain Boundaries," A Collection of OIM Applications, S. I. Wright ed. EDAX Inc., 73-78, (2005).

Crimp, M.A.; Pratt, Jr., W.P.; Bass, J. "Growth and Characterization of Epitaxial Thin Films for Magneto Resistance Multilayers", 2003 CFMR Annual Review, 22-26 (2004).

Bieler, T.R.; Crimp, M.A.; Mason, D.E. "Mesoscopic Measurement And Meodeling of Slip Stransfer Across Boundaries in Anisotropic Metallic Systems", AFRL No. F49620-01-1-0116, , Final report, Dec. 2004.

Nogami, J.; Birge, N.O.; Crimp, M.; Mahanti, S.D.; Hoagn, T.; Katkov, M.V.; Liu, B.Z.; Ohbuchi, C.; Ye, G. "Transport in Self-Assembled Nanostructures," CFMR progress reports 2002-2003 (2003).

Bieler, T.R.; Crimp, M.A.; Mason, D.E.; Semiatin, S.L.; Simkin, B.A.; Ng, B.C. "Use of Crystallography and Electron Microscopy Techniques to Quantify Hetrogeneous Strain and Damage Nucleation Phenomena," Advanced Measurement Methods Web Journal, Society of Engineering Mechanics, Vol. 1 (http://www.sem.org/Afosr/) (2002).