1. 1 Nano Materials and Nano Scale Imaging Prof. Grace Xing Dr. Chuanxin Lian Electrical Engineering Department University of Notre Dame
2. 2 Outline Introduction to Xing Group and Research Discussion of Optics History Ranges of Visual Resolution Scanning Electron Microscopy (SEM) Fundamentals Operation Scheme Atomic Force Microscopy (AFM) Scanning Tunneling Microscopy (STM) Demonstration of AFM imaging
43. Summary on scale and electronics Electronics has come a long way very quickly. Electronic devices are everywhere. Nanotechnology promises to continue this progress into the future. You are the ones to do it! Enjoy!!
44. 44 source How do we see an object? target detector …and often you’ll need a lens
45. 45 Requirements of Vision The light that reaches the eye must have a color between red (760nm) and blue (400nm) – or a mixture of these colors The light that reaches the eye must be sufficiently bright – usually requires a sufficiently bright source www.uvabcs.com/uvlight-typical.php , August 31, 2009 UV UV UV C B A visible light infrared 760 wavelength in nm 3000 290 320 760 400
56. 49 Let’s bounce something else at the surface! e- e- e- e- e- e- e- e- e- e- e- Basic Idea? Animal sight and traditional microscopes collect deflected light Some are “reflected” Some are absorbed
57. 50 Electron Beam Column Beam created from heated filament Beam travels through a vacuum Electro-magnetic fields act as lenses Electron beam hits the sample in a precise location Scattered and “secondary” electrons are detected Beam scans back and forth http://bioweb.usu.edu/emlab/TEM-SEM%20Teaching/How%20SEM%20works.html
58. 51 Electrons Hit Surface and Detection Primary electrons come from the beam Some scatter back, others dislodge electrons http://www4.nau.edu/microanalysis/Microprobe-SEM/Signals.html
59. 52 Example Images http://gsc.nrcan.gc.ca/labs/ebeam/sem_gallery_e.php
63. 56 The powerful, versatile AFM Resolutions: X and Y 2 -10 nm Z 0.05 nm Microstructure of solids: CD, glass beads, circuits Biological samples: skin cross section, viruses, bacteria, blood, DNA and RNA ~30 um scan www.nanotech-now.com/.../antonio-siber.htm Aug 27, 2009
66. 59 Scanning Tunneling Microscopy (STM) Electrons tunnel! With a higher probability than cars STM measures the current created by tunneling electrons Images courtesy of http://www.ieap.uni-kiel.de and www.renault.com
67. 60 Scanning Tunneling Microscopy (STM) C60 “Bucky Balls” Each C60 diameter is ~ 10Å 1 Å = 1x 10-10 m Image courtesy of http://nano.tm.agilent.com
68. 61 Scanning Tunneling Microscopy (STM) Xenon on Nickel Individual atoms? That’s small! Iron on Copper Images courtesy of http://www.almaden.ibm.com