Post on 04-Jan-2016
description
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Large-scale Atomistic Modelingof Laser-assisted Surface Nanostructuring
Xinwei WangDepartment of Mechanical EngineeringThe University of Nebraska – Lincoln
Lincoln, NE 68588-0656
E-mail: xwang3@unl.edu
Phone: 402-472-3089; Fax: 402-472-1465
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Outline
Physical background: laser-assisted STM Design and conduction of large-scale
modeling Unique physical phenomena discovered Current and future work Acknowledgment
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Physical background:laser-assisted STM
STM tipPulsed laser
Si substrate
Enhanced optical field
~10 nm
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Parallel Computation
Enhanced optical field
x
y
z
1 2 3 36354 19.... 18 ........
Distribution of the computation domain on computing points.
More than 200,000,000 atoms are modeled in the system to capture the physical process.
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Parallel Computation
36 of the 52 computing points areused in the parallel MD simulation.
Prairie Wind
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Construction of Prairie Wind
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Completed and current projects
Thermal transport in nanoscale materials
Thermal transport in nanocrystalline materials
Thermophysical properties of single-wall silicon
nanotubes
Surface nanostructuring using laser-assisted
scanning tunneling microscope
Multi-laser beam open-air diamond coating
Long-time nanosecond-laser materials interaction
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Temperature Evolution (side view)
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Sub-surface Nanostructure
Solid
Liquid
Nano-droplet
Stress-induced structural damageBent lattice structure
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Epitaxial re-growth
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Epitaxial re-growth
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Multi-scheme modeling of nanosecondlaser materials interaction
Si wafer
domain II: MD simulation
domain I: finitedifference method
thin Si (~nanometers) layer to provide the connection between the two domains
Si wafer region experiencing phase change
Targeted computational time: 1 s
Targeted domain size: 2 mm
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Multi-laser energy open-airdiamond coating
Substrate
Diamondcoating
C atoms
Velocity, pressure, specie concentration, and temperature are provided by the micro- to macroscopic modeling
Micro/Nanoscale Thermal Science Laboratory • Department of Mechanical EngineeringURL: http://www.engr.unl.edu/~nanolab
Acknowledgement
• National Science Foundation (NSF)
• Office of Naval Research
• Air Force Office of Scientific Research
• Office of Vice Chancellor for Research
Nebraska Research Initiative (NRI)
• Layman Foundation
• Sumitomo Foundation