Download Terahertz Transistors - Oklahoma State University–Stillwater

Terahertz Transistors
NICK OSWALD
ELECTRICAL AND COMPUTER ENGINEERING
AT OKLAHOMA STATE UNIVERSITY
History
 1947 first transistor
 Created by John Bardeen, Walter
Brattain and William Shockley
 Point contact transistor
 Semiconducting material Germanium
 By early 1950’s transistors made its
way into electronics
 Replaced vacuum tubes
Picture from: http://www.porticus.org/bell/belllabs_transistor.html
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

Moore’s 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/Moore%27s_Law#_note-0
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
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/06/1211transistor.html
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/Infotech/17368/?a=f
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

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
Conclusions
 Moore’s Law is continuing to be an influence
 Many new ideas for a THz transistor
 Eventually a complete redesign of the transistor will
be necessary