Award Abstract #0102955
NER: Carbon Nanotube Devices and Integrated Systems

NSF Org:	CCF Division of Computer and Communication Foundations
Initial Amendment Date:	July 7, 2001
Latest Amendment Date:	July 7, 2001
Award Number:	0102955
Award Instrument:	Standard Grant
Program Manager:	S. Kamal Abdali CCF Division of Computer and Communication Foundations CSE Directorate for Computer & Information Science & Engineering
Start Date:	June 15, 2001
Expires:	November 30, 2002 (Estimated)
Awarded Amount to Date:	$100000
Investigator(s):	Chongwu Zhou chongwuz@usc.edu (Principal Investigator)
Sponsor:	University of Southern California University Park Los Angeles, CA 90089 213/740-7762
NSF Program(s):	SPECIAL PROJECTS - CCF
Field Application(s):
Program Reference Code(s):	HPCC, 9216, 1676
Program Element Code(s):	2878

ABSTRACT



PROPOSAL NO.: 0102955

PRINCIPAL INVESTIGATOR: Zhou, Chongwu

INSTITUTION NAME: University of Southern California

TITLE: NER: Carbon Nanotube Devices and Integrated Systems

This is a proposal to design, build and evaluate various novel nanotube devices and

integrated systems. Specifically I propose to make n type field effect transistors (FET),

nanotube p-n junctions, and an integrated single-molecule CMOS inverter. This research

is exploratory in nature; however, if successful, will advance our understanding of the

fundamental properties of nanotubes and produce practical nanoscale devices for the real

world.

There has been a great deal of research into carbon nanotubes in the past few years. P

type field effect transistors have been demonstrated consisting of semiconductive

nanotubes with a silicon substrate backgate separated from the tube by a layer of SiO2.

Despite the utmost interest in developing n type FETs to enable nanoscale CMOS

circuits, the research effort has been hampered by lack of an effective doping method for

nanotubes. I propose to demonstrate a simple, effective and reliable method to

electrostatically dope nanotubes into n type, thus paving the way for n type FETs, p-n

junctions and integrated systems. This new method will employ TiO2 instead of SiO2 as

the gate dielectric. With a dielectric constant of 30 for TiO2, as compared to 3.8 for SiO2,

the gate utilizing TiO2 will be seven times more effective than previously reported, and

our preliminary analysis confirms that with a reasonable gate bias (~ 10 V), a nanotube

can be electrostatically doped into n type, thereby producing an n type FETs.

Furthermore, carbon nanotube p-n junctions will be demonstrated with a split-gate

technique, by depositing TiO2 onto a semiconductive nanotube contacted with source and

drain electrodes, and patterning two gate electrodes atop the TiO2, each covering half of

the tube. By controlling these two gate biases independently, one can tune the left half

tube into p type and the right half into n type, thus creating a p-n junction in between,

which provides an ideal system for studying the depletion and screening in one

dimension.

Finally, a simple integrated system will be demonstrated by attaching an electrode to the

center of a semiconductive nanotube in addition to the source and drain electrodes. This

center electrode divides the nanotube into two segments and serves as the output of the

circuit. The silicon substrate backgate with TiO2 dielectric layer will serve as the circuit

input and be used to tune one tube segment to function as an n type FET and the other

segment as a p type FET, thereby forming the worlds first single molecule inverter.

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