NICK OSWALDELECTRICAL AND COMPUTER ENGINEERING

AT OKLAHOMA STATE UNIVERSITY

Terahertz Transistors

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

itsway 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

imagePicture 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 influenceMany new ideas for a THz transistorEventually a complete redesign of the

transistor will be necessary