Using AFM lithography to fabricate nanoscale electrical devices
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Offered Session:
Both
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Supervisor:
Andrew Dzurak
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Description:
At the Centre for Quantum Computer Technology we fabricate and measure
electrical devices of nanoscale dimensions, with the aim of making
computational components that operate using single electrons. Our ultimate goal
is the fabrication of a P-Si quantum computer.
One experimental technique that is in its infancy for fabricating devices is
atomic force microscope (AFM) lithography. The AFM is a remarkable instrument
in that it can image and manipulate matter at the nanoscale. As an imaging tool
the AFM works by moving a sharp tip (diameter ~ 50 nm) over the surface of a
material with the force between the tip and surface kept constant via a
continuous feedback method. Tracing out contours of constant forces gives an
image of the topography of the surface. However, the tip can also be used to
modify the surface. A particularly elegant method of surface modification is to
apply a negative bias to the tip and dissociate the thin layer of water
molecules that covers the surface of a sample in a humid environment [1].
Dissociated OH- molecules created beneath the tip react with the surface to
form an oxide [2]. The tip is moved over the surface in a pre-defined way so
'patterning' the surface with an oxide that extends down into the sample. The
insulating nature of the oxide allows the patterning of nanoscale electrical
regions at the surface of the material.
This project will explore the use of the AFM lithography method to make
nanoscale electrical devices. The student will determine the experimental
parameters required to most efficiently oxide silicon surfaces and thin metal
films. Architectures for patterning devices directly in silicon or patterning
metal gate electrodes deposited on silicon will then be explored. Towards the
end of the project the electrical properties of these devices will be
characterised. The work will be experimental in nature and will give the
student expertise in working with an AFM, a technique which is becoming one of
the most valuable research tools in condensed matter physics.
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References:
[1] N.J. Curson et al., Applied Physics Letters, 78 3466 (2001).
[2] R. Nemutudi, N.J. Curson et al., Microelectronic Engineering, 57-8 967
(2001).
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Prequisite:
-
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Group Size:
1
School
of Electrical Engineering and Telecommunications
UNSW Sydney
NSW 2052 Australia
Current Students
UNSW 