Transcript Devices for Molecular Electronics (PowerPoint, 6.1MB)

Quantum Dot
Designed Solids
Mott Insulator
MetalInsulator
Transition
U ~ Coulomb Band gap
Weak
coupling
1.5
1.6
1.4
1.3
activation energy ( K )
D
Resistance
I(nA)
In this project, we are trying to
develop quantum dot solids as model
-1.0
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systems for understanding the elecVolts
tronic properties of low-dimensional
solids. At top left is a TEM image of a single monolayer of 7 nm
diameter, organically passivated silver quantum dots, and this is
our model system for study. At top right is a description of how
the electronic properties of this superlattice vary as the
interparticle separation distance is decreased (as quantum
exchange coupling is turned on). When the particles are well
isolated, the system is a Mott insulator, and exhibits single
electron charging characteristics. When the particles are
sufficiently close together, the system passes from an insulator
to a metal. Then, as measured by DC transport, temperature
dependence of the conductivity causes localization phenomena,
which can be then quantified. The various curves at the bottom
left reflect the temperature-dependent DC transport of such a
superlattice as a function of interparticle separation distance.
Inter-particle
coupling
Strong
coupling
NDOS
Heath group contacts
Kris Beverly: [email protected]
Parul Chaudhari:
Kristen Koch:
Also: Raphy Levine, Francoise
Remacle, and Jose Sampaio
Funding: CULAR; DOE
Single e
phenomena
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e
1.2
2R
1.1
Cooperative
phenomena
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area (cm2)
21
e
17
e
Ea from slope
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150 300
Temperature
Current (10-9 Amps)
Heath group contacts:
Yi Luo: [email protected]
Michael Diehl: [email protected]
Erica DeIonno: [email protected]
Greg Ho: [email protected]
Rob Beckman: [email protected]
Nick Melosh: [email protected]
Eric Wong: [email protected]
Also: Fraser Stoddart Group &Hewlett
Packard Corporation
Funding: DARPA; SRC; NSF; ONR
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A
B
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Molecular Electronics
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In this project we are trying to develop molecular electronics-based circuitry for computing applications. This project
involves a broad range of scientific challenges, ranging from developing techniques for device scaling to a few nanometers
length scale to computer architecture and molecular materials development. Clockwise, from top middle left: An artists
version of a molecular switch tunnel junction using [2]catenane molecular switches. The central figure is a distorted
micrograph of a 16-bit molecular memory circuit at device size of ~0.0025 microns2. Right top center is data from a 16-bit
molecular electronic random access memory circuit; far right is a [2]rotaxane molecular switch. Bottom right is a
chemically assembled crossbar circuit using single-walled carbon nanotubes; bottom left is the truth table from an XOR
molecular-based logic circuit; middle left is an artists depiction of a molecular electronic nanoscale crossbar.
Gating Current (Amps)
High throughput proteomics
devices
Laser
VG = -10 mV
VG = 100 mV
4e-11
Optical Layer
2e-11
Nanofluidic
layer
Optical
Splitter
Waveguides
Micromirror
Micropumps
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Time (sec)
0.15
Sensor
Layer
Valves
Nanocell
Sensors
In this collaboration with the UCLA medical school, and
Contact Pads
with the School of Engineering, we are trying to develop bio-device
platforms for the combinatorial interrogation of transmembrane proteins
in highly controlled environments. At top left is a ‘protein’ chip consisting of a lipid bilayer suspended
across a pore micromachined into a silicon wafer. Voltage gating of the membrane reveals single channel
protein gating characteristics. At top right is our targetted device: a library of cellular membranes in which
we utilize fluidics, electronics, sensors, and optics to interrogate the proteins in a host of chemical and
physical environments. At bottom left is a picture of a scanning non=linear optical microscope that we
have constructed for this project. This microscope utilizes femtosecond laser exciation pulses, and
collects the second harmonic generation signal and the two-photon fluorescence signal while retaining full
polarization control over both input and output beams. The protein device is scanned in the x,y plane
using large amplitude piezeoelectronic scanners.
Heath group contacts:
Dr. Xin Yang [email protected]
Dr. Hyeon Choi [email protected]
Rigo Pantoja [email protected]
Ryan Riess [email protected]
Also: Francisco Bezanilla (UCLA medical school) & Rich Sayaklly (UC Berkeley)
Funding: W.M. Keck Foundation