1 Lecture : 9 Carbon Nanotubes and Carbon Nanotube transistors S. E. Thompson Fall 2004
Ref. P. Wong, IBM 2
Ken David, Intel 3
Nanoelectronics Now or Never?" IEDM Evening Panel Discussion, December 14, 4 Session 26: 8:00 p.m. Continental Ballroom 6-9 Moderator: Mark Lundstrom, Purdue University "Nanoelectronics Now or Never?" Traditional 'top-down' microelectronics has become nanoelectronics with device dimensions comparable to those being explored in the new field of ëbottom-up' nano- and molecular electronics. We use the terms, top-down and bottom-up, in a very general sense. Top-down refers to a way of thinking and building that begins at the macro (continuum) scale and pushes to the nanoscale. Bottom-up refers to a way of thinking and building that begins at the atomistic level and builds up to the nanoscale. The top-down approach has already delivered silicon MOSFETs with channel lengths of ~ 5nm, but scaling down device dimensions with commensurate increase in device and system performance is increasingly challenging. Bottom-up technology has demonstrated molecular switches, nanotube and nanowire FET's, NDR and single electron devices, and ultradense memory prototypes. Is bottom-up nanotechnology ready to address the industry's challenges, or is it still long-term research with essentially unpredictable outcomes? This panel will debate the question of what the intersection of top-down and bottom-up electronics will mean to semiconductor technology of the future.
Carbon Nanotube Growth 5
Reason Carbon Nanotubes are Interesting 6 Fundamental physics and chemistry changes when the dimensions of a solid becomes comparable to one or more of these characteristic lengths, many of which are in the nanometer range. Example: Size of semiconducting material is in the order of the wavelength of the electrons and holes. Electronic structure and transport completely changes
Roll Carbon Nanotube from Graphite 7 Ref: Intro to Nanotechnology
Constructing Nanotubes from a Graphene Sheet 8 Chiral angle Zigzag 0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0 11,0 12,0 13,0 1,1 1,1 3,1 4,1 5,1 6,1 7,1 8,1 9,1 10,1 11,1 12,1 13,1 Roll-up vector 2,2 3,2 4,2 5,2 6,2 7,2 8,2 9,2 10,2 11,2 12,2 3,3 4,3 5,3 6,3 7,3 8,3 9,3 10,3 11,3 12,3 Armchair 4,4 5,4 6,4 7,4 8,4 9,4 10,4 11,4 5,5 6,5 7,5 8,5 9,5 10,5 11,5 a 1 6,6 7,6 8,6 9,6 10,6 a 2 7,7 8,7 9,7 10,7 8,8 9,8
9 Semiconductor nanotubes 2,0 3,1 4,2 5,3 6,4 7,5 8,6 9,7 10,8 11,9 5,0 6,1 7,2 8,3 9,4 10,5 11,6 12,7 8,0 9,1 10,2 11,3 12,4 13,5 11,0 12,1 13,2 14,3 14,0 15,1 1,0 2,1 3,2 4,3 5,4 6,5 7,6 8,7 9,8 10,9 11,10 4,0 5,1 6,2 7,3 8,4 9,5 10,6 11,7 12,8 7,0 8,1 9,2 10,3 11,4 12,5 13,6 10,0 11,1 12,2 13,3 14,4 13,0 14,1 15,2 16,0 10,9 9,8 8,7 7,6 6,5 5,4 10,6 9,5 8,4 12,5 11,4 10,3 9,2 13,3 12,2 11,1 10,8 9,7 8,6 7,5 6,4 11,6 10,5 9,4 8,3 13,5 12,4 11,3 10,2 9,1 13,2 12,1 15,1 zigzag armchair 1.0 nm diameter
Some More Properties of Nanotubes 10 1 to 10 nm diameters 10 of um long End capped with half a fullerence molecule Single and multi-wall nanotubes Chirality refers to how the tubes are rolled One-third metallic two-thirds semiconductor Energy gap: 1/(diameter of tube) Diameter of tube increases, bandgap decreases
Extension of C 60, C 70, C 80 80 End closed 11
Multi Wall Tubes 12
Bandgap of Semiconductor Tube 13
s and p Wavefunctions 14 Ref: Intro to Nanotechnology
Carbon Nanotubes: Fullfill Requirements For a Logic Device? 15 Non-linear characteristics Power amplification Concatenability Feedback prevention Basic Logic
C 60 16 Ref: Intro to Nanotechnology
Closed Network From Other Atoms 17 Ref: Intro to Nanotechnology
Si Nano Wires Converted to NiSi 18 Si nanowire Lieber, Nature 2004
Si Nano Wire Transistors 19 Lieber, Nature 2004
Carbon Nanotubes: Fullfill Requirements For a Logic Device? 20 Non-linear characteristics Power amplification Concatenability Feedback prevention Basic Logic
Summary 21
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Carbon Nanotube Lectures 35 What are Carbon Nanotubes and Transistors Metrology Used to Measure Nanotubes Mass spectrometer Transmission Electron Microscopy Scanning Microscopy Scanning electron microscope Scanning tunneling microscope Atomic force microscope How nanotubes are grown Carbon Nanotube Electronic Properties Carbon Nanotube State of the Art Transistors Carbon Nanotube Integration Carbon Nanotube Potential Future Applications Nobel Prize winner Prof. Richard Smalley Lecture on Nanotubes
References 36 Chapter: Carbon nanotube for data processing
What is a Carbon Nanotude Transistor 37
Ref: Jing Guo 38
Nanotechnology 39 The Principles of Physics, as far as I can see, do not speak against the possibility of Maneuvering things atom by atom. It is not an Attempt to violate any laws; it is something, in Principle, that can be done; but in practice, it Has not been done because we are too big Richard Feynman
Nanotechnology History 1959 Plenty of Room at the Bottom Richard Feynman http://www.zyvex.com/nanotech/feynman.html Lecture given to American Physical Society Feynman envisioned Etching lines a few atoms wide Patterning with e-beam Manipulating individual atoms (scanning tunneling microscope) Building circuits on nanometer scale Nanostructures already present in biological systems 40
Micro and Nano History 1 Micro and Nano History 1 1981 Scanning tunneling microscope (STM) Heinrich Rohler and Gerd Karl Binning. 1985 Buckyballs discovered Richard Smalley, Robert Curl, Jr., Harold Kroto 1986 Atomic Force Microscope (AFM) 1991 Carbon Nanotube discovered as part of ERATO program in Japan (1981-2001) Sumio Ijima 1996 NSF commissioned nanoscience and nanotechnology study Recommned National Nanotechnology Initiative 2001 Nanotube logic demonstrated with carbon nanotubes 41
What is a Carbon Nanotube? 42 Start with Carbon Graphite C 60 Single Wall Carbon Nanotubes Multi Wall Carbon Nanotubes Carbon Nanotube Transistors
Start with Carbon 43 Carbon contains six electrons (1s) 2, 2s, 2px,2py, 2pz 1s quantum number N=1 (2 electrons) N=2, four electrons s orbital spherically symmetric about nucleous p directed charge distribution s and p form chemical bond Ψ = s + λp Solid carbon two main structures Diamond sp 3 109 degree bonds Graphitic sheet sp 2 120 degree bonds. Each bond in same plane Graphite s, px, py Sheets held together by weaker van der Waals Forces
Discovery of C 60 44 Soccer ball-like molecule containing 60 carbon atoms Motivated by understanding ligh transmission through interstellar dust Optical extinction: absorption and scattering of light from interstellar dust C60 envisioned by theoretical chemist High powered pulsed laser simulate conditions of hot carbon Prof. Richard Smalley (Rice) observed mass number 720 mass spectrometer (carbon mass #12) Smalley won Nobel prize
ATM or STM Used to Determine Chirality 45