Nick Oswald

1
Terahertz Transistors

• Nick Oswald
• Electrical and Computer Engineering
• at Oklahoma State University

2
History

• 1947 first transistor
• Created by John Bardeen, Walter Brattain and
  William Shockley
• Point contact transistor
• Semiconducting material Germanium
• By early 1950s transistors made its
• way into electronics
• Replaced vacuum tubes

Picture from http//www.porticus.org/bell/belllab
s_transistor.html
3
History Continued

• Integrated Circuit
• 1958 Jack Kilby
• Combined electrical devices on a single chip
• Planar Technology
• 1958 Jean Horni
• Created a transistor with a flat profile
• IC with Planar Technology
• 1959 Robert Noyce
• Combined IC and Planar technology

4
Moores Law

• Published in 1965 by Gordon Moore
• Has been extremely accurate to this point
• Inspired the progression of technology
• Has been used to predict the feature size and
  speed of transistors

Picture from http//en.wikipedia.org/wiki/Moore27
s_Law_note-0
5
Proposed THz Transistors

• Traditional Transistor But smaller features
• December 2006
• Milton Feng
• University of Illinois at Urbana-Champagne
• Ballistic Transistor
• August 2006
• Quentin Diduck
• University of Rochester
• Carbon Nanotube Field Effect Transistor (CNTFET)
• Many Different Designs
• June 2007
• Yury A. Tarankanov and Jari M. Kinaret

6
Traditional Transistor with Smaller Feature size

• Switching Speeds
• 845 GHz when chilled to -55 C
• 765 GHz when at room temperature
• Fastest Transistor when proposed
• Base Mesa
• Old Design 1.5µm
• New Design 550 nm
• Measured using an SEM image

Picture from http//www.news.uiuc.edu/NEWS/06/1211
transistor.html
7
Ballistic Transistor

• Operation
• 0 or 1 based on the direction of flow
• Direction changes based on the field applied to
  the transistor
• Deflects electrons off a triangle
• Electrons flow in a plane
• Characteristics
• Materials
• indium gallium arsenide
• indium phosphide
• Gallium arsenide
• 70nm feature size
• Use etching to create the triangle

Picture from http//www.technologyreview.com/Infot
ech/17368/?af
8
CNTFET

• Many different designs
• Carbon nanotube ring
• Semiconducting characteristics
• Conducting characteristics
• Carbon nanotube cantilever
• Single walled nanotube structure (SWNT)
• Lying on a layer of Silicon dioxide
• Attached to the drain and source
• 2 separate designs using a metallic multi-walled
  nanotube structure (MWNT) acting as gate
• Doubly clamped
• Singly clamped

9
CNTFET continued

• SWNT
• Length 1000nm
• Diameter 1.7nm
• MWNT
• Doubly Clamped
• Length 2000nm
• Support height 30nm
• Singly Clamped
• Length 1000nm
• Support height 40nm and 60nm
• Gate bar height 25nm and 40nm

Picture used from Yury A. Tarakanov, Jari M.
Kinaret, A Carbon Nanotube Field Effect
Transistor with a Suspended Nanotube Gate, Nano
Letters, Vol. 7, No. 8, pp. 2291-2294, June 2007
10
Conclusions

• Moores Law is continuing to be an influence
• Many new ideas for a THz transistor
• Eventually a complete redesign of the transistor
  will be necessary