Dr. Robert Cook

Research Interests

• Mechanical properties measurement tools, methods, standards, and data needed for materials and components in nanotechnology applications, including microelectronics, magnetic storage, microelectromechanical systems (MEMS), and nanoparticles
• Applications of advanced nanomechanical measurement tools, such as scanning probe microscopy, nanoindentation, and MEMS-based test vehicles, to solve commercial nanotechnology problems
• Fracture mechanics—particularly the effects of microstructure, residual stress distributions, and crystalline anisotropy on crack propagation, strength, and flaw tolerance in brittle materials, especially silicon
  
• Contact mechanics, including instrumented indentation testing—“nanoindentation”—for measurement of elastic, plastic, fracture, and viscous properties of all materials at ultra-small scales
• Adhesion mechanics, and the effects of interfacial surface forces, capillary menisci, and molecular layers on the mechanical and electrical properties of ultra-small contacts
• Stress and strain metrology for nano-scale measurements, including the use of Raman spectroscopy and electron and X-ray diffraction
  
• Thermomechanics, with a focus on irreversible (non-equilibrium) isothermal fracture (often called “slow crack growth” or “stress-corrosion cracking”) and its effect on the reliability of components containing brittle materials

Figure 1 (left): Vickers indentation in Si(001) showing fracture and shear-fault controlled plastic deformation; Figure 2 (center): Simulation using a self-consistent adhesion model of nano-scale Si-Si contact at pull-off instability; Figure 3 (right): Confocal Raman microscopy image of residual indentation stress field in Si (red indicates compression).


Postdoctoral Research Opportunities in my Group

 
Contact me if you are interested in a National Research Council Postdoctoral Research Associate Fellowship in any of the above areas (United States Citizenship required).

Current opportunities include the following

Develop new nanomechanics techniques involving scanning probe microscopy, especially atomic force microscopy, in static, dynamic, normal, or lateral modes to measure surface forces and small-scale adhesion and friction. For more information … 

Develop new experimental methods and analysis for studying nanoscale fracture phenomena that do not rely on the direct imaging of the cracks, but instead use an indenting probe (or other nanomechanical apparatus) as a sensitive “crack-compliance” detector. For more information …

Predict lifetime of microelectromechanical systems, nanoelectromechanical systems, electronic components and devices, film actuators, and sensors under service conditions. For more information …

Optimizing the yield and reliability of devices that depend on nanoscale “strain engineering” is made difficult as is the identification of the “stress signatures” of plastic and fracture defects that control device performance and reliability. In this project a confocal Raman spectroscopy technique is being developed that allows stress measurement at the nanoscale, which in turn enables measurement of stress-intensity factors at crack tips and toughness to be estimated at the nanoscale. For more information …

Although much research is in progress to elucidate the interaction of laser radiation with a nanoparticle, and in the use of this interaction for the thermal ablation of tumors, little has been done to understand the influence of the local nanoparticle distributions or of metal-shell defects on the process. This project seeks to elucidate the influence of particle ensembles and nanoshell defects on the local plasmonic heating of gold nanoshell particles. For more information …

Awards and Honors

• Department of Commerce Bronze Medal for Superior Federal Service, 2011
  
• Department of Commerce Silver Medal for Scientific/Engineering Achievement, 2008
• Richard M. Fulrath Award, 1999
• Fellow, American Ceramic Society, 1998