Two and three-dimensional nanoscale
structures for molecular electronics
Sean Glass EE ’03 with Dr. Ilona Kretschmar
and Dr. Mark Reed
Senior Project 2002-2003
Abstract
Molecular electronics has been hailed as the next step in the
creation of faster computer chips and denser memory technologies.
One proposed architecture for molecular computing currently being
explored by the research groups of Mark Reed at Yale and Jim Tour at
Rice is the Nanocell. Key to this architecture is a 2d array of
gold nanoparticles that are connected by so called molecular wires.
The nanocell is "programmed" to perform a certain logic operation.
My research developed from the need to create a 2d close packed
array of gold nanoparticles that could be formed in the center of
the nanocell. Several methods where explored and efforts where made
to understand the different variables that seem to play a role in
the ordering and growth of 2d and 3d structures using the assembly
method that was explored in detail.
Nanoparticle Deposition
Sean Glass EE ’03 with Dr. Ilona Kretschmar and Dr. Mark Reed
Overview
During the fall and spring semesters of the ’02-03 academic year, I participated in
research in the research group of Professor Mark Reed. My work focused on determining
a self-assembly method to create an ordered two or three-dimensional structure composed
of gold Nanoparticles.
Motivation
“Conventional silicon will reach some fundamental limits in the next few years. There are
physical constraints on the size of circuits in computers. Silicon has surpassed the
“Moore’s law” forecast of a doubling of device performance and density every one and a
half to two years. There are unavoidable obstacles involved in this continual downsizing
of silicon. These limits will be reached in the next five to ten years as acknowledged by
the industrial giant, Intel Corporation. The basic physical limits include charge leakage
and a loss of band structure at miniscule sizes. This is not a problem with
molecules because they have relatively large energy level separations at room
temperature and at the nanometer-size due to their discrete orbital levels. This makes
them independent of broad band properties. These physical problems arise as
conventional circuits shrink in size. In addition to the physical constraints, there are
financial obstacles. It currently costs $2.5 billion to build a fabrication line for a
traditional computer. By 2010, that figure is projected to rise to $15 billion. In 2015, it
will cost in excess of $100 billion. These costs will clearly become prohibitive.”1
The solution that is currently being explored by different research groups around
the country is molecular based
electronics. Professor Reed’s group is
part of a group that is exploring the
possibility of creating a molecular
computing system based on an
architecture that is referred to as the
Nanocell. “The nanocell was inspired by
a desire to create a molecular electronics
model that takes into account the behavior of molecules. That is, a model that can be
realistically fabricated… The nanocell is the lowest level logic device in the proposed
molecular computer. Its size is approximately 1µm2… The network within the nanocell is
an array of gold nanoparticles (some metal other than gold could be used) connected with
molecules.”2
As mentioned above, a two-dimensional gold Nanoparticle array is an important
part of the Nanocell structure. Previously, My research focused on selecting and
understanding a method that results in the self-assembly of a two or three-dimensional
hexagonal close packed arrays of 60nm Au (Gold) Nanoparticles.
The summary that follows outlines the work that I did during the first and second
semesters. An appendix includes a summary of experiments done during the second
semester. I have also included the protocol that I am currently using to perform the next
step in the research. It is our hope that after the experiments detailed in the protocol we
may be able to publish our results thus far.
Acknowledgements
I’d like to thank Dr. Reed for the opportunity to work in his group. I have
thoroughly enjoyed the opportunity to partake in research that is at the cutting edge of
electrical engineering, computer science, material sciences, and chemical engineering.
The lessons that I have learned in terms of critical thinking, experiment planning, process
planning, and document research will surely be valuable after Yale.
Dr. Ilona Kretzshmar has been a truly wonderful mentor over the last two
semesters. I am thoroughly thankful that she put up with me and was willing to guide
this work as it progressed. Her scientific understanding and willingness to work with me
to pursue new ideas and to engage what she might describe as my unbounded, but
sometimes slightly un-organized enthusiasm has enabled me to have a wonderful
experience with this project. I am sure she will have great success in whatever direction
her work takes her.
Fall Semester 2002- Nanoparticle Assembly Project
Sean Glass & Dr. Ilona Kretzschmar
Objective: Develop a procedure for creation and transfer of large area nanoparticle arrays
(areas of up to 10000 m2) made of gold nanoparticles or silica spheres (>500 nm). Once
the procedure for array formation is controllable, transfer of these films via PDMS
stamping will be attempted. These two dimensional films may, for example, find
application in optical device fabrication (photonic band gap crystals), as top contacts for
molecular electronics, as nanocell filling, as templates for nanoparticle array formation
(nanosphere lithography, NSL), etc. .
History:
Formation
of
a
white rim was observed on
chips that had been treated
Hexagonal
closed-packed
.......
with 100 nm TedPella gold
nanoparticle solution. Close-
assembly of
up SEM images (see inset
100 nm gold
Figure 1) revealed that the
nanoparticles
white rim is comprised of
nanoparticle arrays, that are
in some spots more or less
hexagonal
Figure 1.
closed-packed
(hcp).
Experimental plan:
1) Search literature for methods used for microsphere array formation.
(in progress)
2) Understand physics behind array formation, i.e., parameters that
influence/guide array formation.
(in progress)
3) Test methods and evaluate, which method(s) is(are) most suitable
for our interests.
(in progress)
4) Build stable set-up that allows reproducible experimental conditions. (in preparation)
5) Vary parameters such that film formation is tunable as needed.
(not started)
6) Develop PDMS stamp and film transfer protocol.
(not started)
Results as of 01/09/03:
1) Methods for nanoparticle assembly
Four methods crystallized as the main used ones from the literature search. These
methods are (i) the spin-coating method,3 (ii) the tilting method,3 the (iv) vertical
deposition method,4. and (iii) the tapered cell method.5 All of these methods have been
optimized for microspheres such as silica spheres, latex spheres, or polystyrene spheres
with a size range from 0.3 to 1 m.
(i) spin-coating method: involves a set up, where the support is in a vertical
position mounted on a spinner. A drop with the microsphere solution is dropped onto the
support and then spin speeds between 100 and 1000rpm are used to induce array
formation (time ~1min max). The assembly is then left to dry in a lidded container, which
warrants a constant evaporation rate. Film formation can be controlled by spin-speed,
temperature of the sample at the beginning, and concentration of microsphere solution.
Maximum area covered: 91,000 m2.
(ii) tilting method: Support on which microsphere array should from is mounted
on a tilted ramp in a closed-lid box (the latter warrants consistent evaporation rates).
Solution with microspheres is dropped onto
the support and runs down the support leaving
behind a film of close-packed microspheres.
The packing of the film is determined by the
tilting
angle,
whereas
the
microsphere
concentration controls mono, di- or multilayer formation. Temperature of support prior
to assembly also influences array formation. Maximum area covered: 8,100 m2.
(iii) vertical deposition method (extreme case of tilting method) similar to the
tilting method, the vertical deposition method involves the suspension of the substrate so
that it is roughly vertical in a solution. As the solution evaporates, particle arrays form on
the substrate. This method relies on a balance between the solution evaporation rate and
the particle sedimentation.
(iv) tapered-cell method: Here a
reservoir is filled with a microsphere
solution. Next, the cell is connected to a
tapered cell as shown in Figure 3. The cell
is filled with solution and left alone such
that the solvent evaporates. As a result of
Figure 3.
capillary forces (see below) a monolayer film of microspheres forms. Concentration of
the solution, temperature of the support as well as ambient temperature during
evaporation are the main parameters determining the array formation. Maximum areas
covered: ~3cm2!
2) Physics governing microsphere/nanoparticle array formation with the tilt method.
It appears that array formation and
structure is dependent on the
velocity of the receding substratesuspension-air contact line.
The
way to continuously form a 2d
particle
array
“unidirectional
is
to
growth
develop
of
the
arrays, where the arrays leading
edge is a straight line advancing
with the rate of array growth.”6 Dimitrov and Nagayama present a kinetic model of array
growth that is based on this principle.
This equation incorporates the parameters that govern the
overall process of an array growth. The parameters are: (i) the
water evaporation rate je, which depends on the temperature
and relative humidity of the surrounding atmosphere, (ii) the particle volume fraction in
the suspension Ф, (iii) the thickness of the forming 2D arrays (i.e., the number of layers
in the array and the diameter of the particles), and (iv) the race of the array’s growth vc
using different angles.
All of the articles have reported that an extremely hydrophilic surface is important
because the formation of a wetting film is a necessary condition for array initiation. We
are not sure if the kinetic model described above would apply to all array formation
methods described above, but our hypothesis is that they are governed by similar laws.
3) Testing of methods
First approach was to use old silicon wafer pieces and look at the general dependence of nanoparticle array formation as a function of support angle. The three
geometries used are depicted on
the right. SEM data of the pieces
taken after evaporation of the
flat
medium
high
solution and 1 min cleaning in
distilled H2O yield the following general information.
flat
medium
high
In the flat geometry, small, densely-packed clusters of nanoparticles form randomly on
the surface of the chip (Note there was no solution border on the chip – thus no rim
formation). Much larger hexagonal close-packed nanoparticle arrays from in the medium
angle set-up. Interestingly, several of these lines with closed-packed structures are found
always parallel to the solution front. The high-angle set up yields larger areas of
nanoparticle arrays, but much less dense packed. From this we conclude that a mediumangle approach is the one that will most likely result in close-packed, large area
nanoparticle arrays. Further, we noticed that a lot of particle settled on the bottom of the
flasks due to gravity.
Second, the support was changed from silicon wafers to microscope cover glass
slides for the lack of a better support material. However, it was also interesting to see, if
there would be a difference between silicon and glass as support material. In order to
reduce the disturbance of the array formation by gravity-induced settling of the particles,
we decided to increase the evaporation rate using an oven. Due to experimental
constraints only the vertical and horizontal approaches were possible at that point. The
pictures shown in the following were taken with the Cascade Microprobestation
Microscope.
Vertical setup: For the vertical setup cleaned glass slides were dangled into a solution
containing 100 nm TedPella nanoparticles. The solution and slides were then added to a
oven set at a temperature of 50ºC. After all solution had evaporated, the slides showed
formation of brownish films on both
sides, which were interrupted by
darker
lines
Interestingly,
(see
the
Figure
5a)
topmost
line
a
b
c
d
showed a yellowish color under the
microscope. We further noticed that
light was reflected or deflected
towards the sides of the slides when
the light beam hit the film areas
pointing towards a continuous film
that has optical properties.
Figure 6 shows the slides before and
Figure 5
unrinsed
after rinsing of the slides for one
minute in DI water. As becomes
obvious upon closer inspection, the
rinsing washes the larger dark spots
away. Unfortunately, any attempts of
characterizing these layers further
using AFM failed (see Figure 7).
Figure 6
Figure 7
rinsed
Horizontal setup: For the horizontal setup, a big drop with nanoparticle solution was
dropped onto a freshly cleaned glass slide. The slide were then transferred to the oven
and left inside the oven until all solvent had evaporated. Large rings of particles formed
with smaller particle barriers within the outer ring. Figure 8 shows parts of the outer and
innermost rims and reveals the pronounced differences between the two types of barriers
formed.
innermost rim
outermost rim
Figure 8
First experiments with SiO2 microspheres have been performed and similar film
formation is observed.
4) Build stable set-up that allows reproducible experimental conditions.
The technical drawings for a tilted setup are in preparation. We thought of having them
machine a Teflon/Delron sheet with a 3x3 or 3x4 matrix of squares which can hold a 1cm
die each. This sheet can be hung onto a metal plate that is connected to a z-manipulator of
some sort. Moving the manipulator up and down will then cause different tilting angles
(see schematic in Figure 9).
z

Figure 9
Spring Semester ‘03 – Control of Self-Assembly Caused by Capillary Forces During
Droplet Evaporation
Introduction
The following is the text for an abstract that we submitted for the 226th ACS National
Meeting, New York September 7-11, 2003.
Two- and Three-dimensional Nanoscale Structures for Molecular Electronics
Ilona Kretzschmar, Sean Glass, and Mark A. Reed
Department of Electrical Engineering, Yale University, New Haven, CT 06520
The need for miniaturization of circuitry in order to obtain denser microelectronics has
recently led to the investigation of molecules as electronic elements. The molecules used
for such elements are usually a few nanometers long and less than a nanometer wide.
Most industrially applied processes, however, are based on lithographic techniques and
are limited to a spatial resolution in the upper nanometer range, thus presenting a problem
with respect to interconnection of the molecular assembly to the outside circuitry.
Feature sizes down to the 10 nm scale have been achieved by electron-beam lithograph,
but the processes are often small-scale and
have a low throughput. Self-assembly of
nanometer-sized objects offers an
alternative approach to controlled
formation of 1D-, 2D-, and 3D-structures
in the few nanometers to hundreds of
nanometer range, bridging the gap
between atomic manipulation and modern
lithography. In addition, self-assembly processes convince with their simplicity and low
processing costs.
Here we report results on the self-assembly of 60 nm charge-stabilized gold nanoparticles
into densely packed arrays on SiO2 surfaces (see Figure). The arrays are formed at the
periphery of nanoparticle-containing droplets that are placed on a freshly cleaned SiO2
surface and are allowed to dry. Parameters such as sample temperature, humidity, and
contact angle are varied to control the evaporation rate and thus influence the
nanoparticle assembly process. The main driving force for the assembly is a convective
flow from the center of the drop to its rim.7 Electrical characterization of the nanoparticle
arrays is in progress. The results are discussed in the context of general applications of
nanoparticle assemblies in molecular electronics.
Methods
During the spring semester, the research I pursued focused on one particular method of
creating 2D and 3D gold Nanoparticle assemblies. Initially, I evaluated the method using
solutions with different types and sizes of Nanoparticles. We determined that the results
we saw with 60nm Au Nanoparticles (NP’s) were particularly interesting due to very
distinct layer formations at the rim and thus research towards the end of the semester and
the summer has been focused on attempting to understand the layer formation process
and to determine whether it can be controlled in order to create a simple, repeatable way
to produce arrays of Nanoparticles that have a well defined edge structure. If we are able
to achieve this goal, the process may have applications both in molecular electronics
(both in the Nanocell project and elsewhere), as well as in optics through its use as a
mold for the creation of photonic band-gap structures.
Tilting Setup
A setup was created that could be adjusted to obtain various degrees of tilt. When a
droplet is placed on a substrate on the setup, the contact angle on the top and the bottom
of the droplet will be different. This leads to a slightly different evaporation profile at
different parts of the droplet. Our belief was that there would be an optimum tilting angle
for the formation of a monolayer of gold Nanoparticles.
Key Features of the tilting setup shown opposite were:

Simple & Controllable

Reproducible

Highly Adjustable

Oven Capable
Substrate
I used a processed silicon wafer as the substrate. Before NP deposition, the substrate was
cleaned using UV Ozone for 30 minutes and Ethanol for 10 minutes. By utilizing these
methods to clean the silicon surface, an extremely hydrophilic surface was created. A
hydrophilic surface is extremely important with this method because the pinning of the
edge of the droplet is what causes the self assembly of the Nanoparticles at the edge of
the droplet.
Results
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
The experiments that used both Au NP’s and Polyspheres demonstrated that the optimum
tilt angle for assembly was no 1/2 turns for the tilting setup. This was an angle that was
very close to 0 degrees of tilt. The Polyspheres were assembled into organized
hexagonally close packed layers more easily than the Au NP’s. A more interesting result
from these experiments was that with this setting, distinct steps formed around the rim of
the drop. These layers had very consistent widths, and progressions from monolayer to
bilayer, to trilayer, etc.
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
Research into understanding the physic behind how the layers at the rim form was
undertaken. The primary source used to understand the physics involved was “Capillary
flow as the cause of ring stains from dried
liquid drops” by Robert D. Deegan*, Olgica
Bakajin*, Todd F. Dupont†, Greb Huber*,
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
Sidney R. Nagel* & Thomas A. Witten*
Nature, October 22 1995. Further literature
research is ongoing.
It appears that the layer formation might be able to be controlled by controlling
the evaporation profile of the droplet. In a more in depth article by Deegan et Al. it is
demonstrated on a macro-scale how evaporation profile can affect contact line deposition
of solids in solution.8
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
I believe that by varying the evaporation profile and adjusting it by using
temperature, we may be able to control layer (and thus step) formation. The experiments
detailed in the section “Future Experiment Protocol” outlines a set of experiments that
will allow us to make an initial assessment of whether or not this hypothesis is correct.
Further Research
There are several directions that future research in this area could be pursued. I believe
all would be beneficial. These include

Development of a computer simulation to enable
engineers to simulate Nanoparticle deposition due to
capillary forces created during evaporation of a
Nanoparticle solution.

Exploration of the affects of ultrasonic vibration during
particle deposition. In a quick experiment that I did to
test this, there were somewhat promising results.

Experiments focused on varying the evaporation profile
Au NP’s self-assembled while
being ultrasonically vibrated
and relating the evaporation rate and profile to the formation of Nanoparticle
layers (see Future Experimental Protocol that follows)
Future Experiment Protocol
Experiment Protocol
5/18/03
Controlled Self Assembly of 60nm Au Nanoparticles by adjusting the evaporation
profile and temperature
Goal
Establish the relationship between evaporation profile and temperature to the creation of
ordered layers of Au 60nm Nanoparticles, assembled due to capillary forces created due
to the pinning of a droplet, at the edge of a droplet.
Experimental Setup
The “tilting” setup previously used successfully to create ordered assemblies of 60nm
Au. NP’s will be used and set at 0 1/2 rotations. Silicon wafer will be diced and before
deposition will be cleaned by UV Ozone for 30 minutes and 10 minutes ethanol wash.
The sample will be placed in a covered container with the top on in the water bath, which
will be used to control the temperature. A thermometer will be placed in the container
next to the “tilting” setup. The temperature will be recorded at the beginning and at the
end of the experiment. The amount of time until the drop loses it’s droplet shape will be
recorded and the total time until the droplet dries will be recorded. The amount of
solution that will be placed on the silicon sample will be 2.5 microliters. The diameter of
the rim formed from top to bottom and side to side will be measured.
Steps
1. Dice Silicon (piece should be ~ .75cm x .75 cm)
2. Turn UV Ozone on for 10 minutes to warm up
3. UV Ozone for 30 minutes
4. Turn on water bath and place container in water bath with top off.
5. Set temperature of water bath
6. Place sample in Ethanol for 10 minutes
7. Dry using “guster”
8. Place sample in on tilting setup
9. Place tilting setup with sample in container in water bath
a. If evaporation profile 3
10. Place thermometer next to tilting setup in the container
11. Deposit 2.5 microliters of 60nm Au Nanoparticle solution
a. Place cover with whole on droplet for evaporation profile 2
12. Record temperature
13. Place top on container
14. Observe when the solution first breaks from the initial drop circumference.
Record this time as the time when the droplet first loses its shape
15. Record time when droplet evaporation is complete
16. Mark lower left hand corner of sample with a dot
17. Rinse sample in H2O for 1 minute
18. Measure width of rim from top to bottom and left to right
19. Store sample in plastic container
20. The top, bottom, left, and right parts of the drop will be observed using SEM
21. The thickness of the rim and the number of layers will be observed
a. Pictures taken can potentially be analyzed via 2D fourier transform to
determine the degree to which the arrays that form have regular order.
Variables
Temperature
The temperature will be varied by using the water bath. The temperatures used will be
20 C
68 F
25C
77 F
30C
86 F
35C
95 F
40C
104 F
Evaporation Profiles
Three evaporation profiles will be used
1. Normal – Sample placed on tilting setup and placed in container in water bath to
dry
2. Inverse – cover placed over sample with a whole centered over the middle of the
droplet so that
3. Uniform – Water placed around the sample so that it is at the same level as the
silicon
Experiment Grid
The number in the grid represents the number of samples to be created under each
condition
Evaporation Profile
Temperature
20
25
30
35
40
Normal
2
2
2
2
2
Inverse
2
2
2
2
2
Uniform
2
2
2
2
2
Total of 30 Samples
2 additional control samples at room temperature, which are dried in the dececateur, not
the water bath and the temperature recorded, will be created.
Appendixes

Experiment List

Images

References
Raw Data
Experiment List
Date
Sample Name
Particle Type
Calculated
Angle
Half Rotations
Concentration Volume of Solution
Temperature
Start
Temperature
End
Average
Temperature
Drying Time
2/18/03 Au25088
Au250
88
33
1 2.5 microliters
0
Au10088
Au100
88
33
1 2.5 microliters
0
Au6088
PS45088
PS10088
PS5088
Au60
PS450
PS100
PS50
88
88
88
88
33
33
33
33
1
1
1
1
microliters
microliters
microliters
microliters
0
0
0
0
2/19/03 Au25044
Au250
44
19
1 2.5 microliters
0
Au10044
Au100
44
19
1 2.5 microliters
0
Au6044
PS45044
PS10044
PS5044
2/23/03 Au2500
Au1000
Au600
PS4500
Au60
PS450
PS100
PS50
Au250
Au100
Au60
PS450
44
44
44
44
0
0
0
0
19
19
19
19
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
0
0
0
0
0
0
0
0
PS100
0
1:40 2.5 microliters
0
PS50
Au100
Au100
Au60
PS450
PS100
0
0
22
22
22
22
1:40
1
1
1
1:40
1:40
microliters
microliters
microliters
microliters
microliters
microliters
0
0
0
0
0
0
PS50
22
1:40 2.5 microliters
0
PS1000
PS500
2/24/03 Au1000
2/27/03 Au10022
Au6022
PS45022
PS10022
PS5022
1
1:40
1:40
1:40
1
1:4
1
1:40
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
Au100
0
1
0
2- 100nm
Au100
0
1
0
3 - 100nm
Au100
1
0
2/27/03 1 - 100nm
Top Drying Time
Comments on Experiment
Conducted at room temperature. No
temperature measurements or drying time
records were kept. The samples were
placed in the dececateur to dry. Silcon
was cleaned with 30 min UV Ozone then
10 min or more ethanol wash
Conducted at room temperature. No
temperature measurements or drying time
records were kept. The samples were
placed in the dececateur to dry. Silcon
was cleaned with 30 min UV Ozone then
10 min or more ethanol wash
Conducted at room temperature. No
temperature measurements or drying time
records were kept. The samples were
placed in the dececateur to dry. Silcon
was cleaned with 30 min UV Ozone then
10 min or more ethanol wash. 250 and
100 au solutions looked funny
rt in dececateur, uv - oz - ethanol
Conducted at room temperature. No
temperature measurements or drying time
records were kept. The samples were
placed in the dececateur to dry. Silcon
was cleaned with 30 min UV Ozone then
10 min or more ethanol wash
Used PDMS stamp and an oil pastel crayon
to roughly pattern a glass surface. Placed
100nm au solution in the patterned areas.
Placed in dececateur. Glass slides were
cleaned before hand with uv-zone 30 min
and ethanol 10 min. After they dried, the
oil pastel was removed using acetone and
by wiping with a kim-wipe
3/13/03 Au600 Old
Au60
0
1 2.5 microliters
0
Au1000 old
Au100
0
1 2.5 microliters
0
Au1000 new
Au100
0
1 2.5 microliters
0
Au600 Old
Au60
0
1 2.5 microliters
0
Au100 old 2drops
Au100
0
1 2.5 microliters
0
Au60 old 2 drops
Au60
0
1 2.5 microliters
0
Au 100 old 3 drops
Au100
0
1 2.5 microliters
0
Au600 old 3 drops
3/16/03 Au10011 Old
Au10011 New
Au6011 Old
PS45011
PS10011
PS5011
Au60
Au100
Au100
Au60
PS450
PS100
PS50
0
11
11
11
11
11
11
3/19/03 NC1
Au60
0
1 .5 microliters
0
NC2
Au60
0
1 .1ml
0
Au60ha
Au60
0
1 2.5 microliters
0 10-20 seconds
Au60hb
Sd1
Sd2
Au60
Au60
Au60
0
1 2.5 microliters
1 ?
1 ?
0 10-20 seconds
0
0
1 ?
1 ?
0
0
1 ?
0
1 ?
0
3/20/03 Sd3
Sd4
Au60
Au60
sd5
Au60
sd6
Au60
3/24/03 Au600h1
Au600h2
Au600h3
Au600h4
Au600h5
Au600h6
3/26/03 Au600h7
Au600h8
Au600h9
Au600h10
Au600h11
Au600h12
Au600h13
0
0
0
0
0
0
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
0
0
0
0
0
0
0
0
0
0
0
0
0
4/3/03 U1
Au60
n/a
U2
4/7/03 Au600h14
Au600h15
Au606RT
Au606rt2
au6012rt
au6012rt2
Au600 normal
Au600 1:1
Au600 1:3
4/9/03 Au6012rt
au6012rt2
Au6018rt
au6018rt2
au6012rt12
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
Au60
n/a
1
1
1
1
1:40
1:40
1:40
1
1
1
1
1
1
1
1
1
1
1
1
1
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
0
0
0
0
0
0
0
74
74
178
176
122
122
70
70
123
122
177
175
91
72
72
173
172
117
117
70
70
120
119
175
172
88
1 2.5 microliters
18
18
6
6
12
12
0
0
0
12
12
18
18
12
1
1
1
1
1
1
1
1
1:1
1:3
1
1
1
1
1:1
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
microliters
67
67
68
68
67
67
67
67
67
65
65
66
66
65
67
67
67
67
67
67
67
67
67
65
65
66
66
65
UV - ozone 30 min. Ethanol 10 min.
Placed in dececateur. For multiple drops,
the samples were rinsed in between
multiple drops. They were not placed in
UV-ozone or ethanol again. Old and new
solution refers to the old solution (which
we thought might be bad, and the new
solution straight from the Ted Pella bottle)
~10
~10
~10
~10
~10
~10
minutes
minutes
minutes
minutes
minutes
minutes
Uv ozone 30 min, ethanol 10 min. Placed
on tilting setup.
Placed in acetone for 15 min. Rinsed
briefly in deionized water. UV-Ozone for
30 min.
UV-Ozone 30 min. Ethanol 10 min. Placed
in oven to 30
dry.min.
LeftEthanol
in oven10
formin.
2 min.
UV-Ozone
Placed
as small a drop as possible using glass
syringe
used silicon that was left in ethanol from
3/19 for Sd3-6. 2 drops on lower right
Very small drop
6 drops on top left and lower right… Drops
placed inside of previous drop ring filling it
completely.
As drop is about to dry, add more solution
to it.
73
73
175.5
174
119.5
119.5
70
70
121.5
120.5
176
173.5
89.5
0:08:02
0:08:36
0:00:34
0:00:38
0:01:56
0:01:55
0:05:00
0:05:56
0:01:01
0:01:04
0:00:20
0:00:29
0:03:41
0
0:05:20
0
67
67
67.5
67.5
67
67
67
67
67
65
65
66
66
65
0:05:00
0:08:56
0:09:34
0:09:00
0:08:57
0:09:24
0:09:48
0:09:37
0:10:47
0:09:20
0:11:26
0:10:52
0:08:53
0:10:46
0:12:16
used samples that were left in ethanol
from 3/19. Used a hot plate to heat the
area around the sample holder. Temp
measurment from therm. on the hot plate.
Hot plate was under the fume hood.
same as 3/24, but used newly cleaned
silicon samples rather than left over
samples kept in ethanol. Also - opened
fume hood windows ~4 minutes into
drying of h7. It was open for h9-h13
Uv-ozone 30 min, ethanol 10 min. Placed
sample in bottom of beaker. Placed
beaker in water in the ultrasonic bath
Uv-ozone 30 minutes, ethanol 10 minutes,
Placed on sample holder on hot plate. Not
in the fume hood.
Uv ozone 30 min, ethanol 10 min. Placed
on tilting setup. Not in dececateur
0:09:00
0:07:50
0:05:50
0:06:50
0:10:15
UV-ozone. Ethanol 10 min. On desk in the
afm room on the sample holder. Top
drying time is the time when the original
top contact line changes.
Images
March 11th
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
March 18th
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
March 21
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
March 25
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
March 27
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
April 4
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
April 11
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
References:
1
Husband, Summer M. “Programming the Nanocell, a Random Array of Molecules.” April, 2002.
2
Ibid.
3
For example: V. Ng, Y. V. Lee, B. T. Chen, A. O. Adeyeye Nanotechnology, 2002, 13, 554.
4
L.M Goldenberg, J. Wagner, J Stumpe, B.-R. Paulke, E. Gornitz Materials Science and Engineering, 2002, 405-408
5
For example: T. Yamasaki, T. Tsutsui Jpn. J. Appl. Phys. 1999, 38, 5916.
6
A. Dimitrov, K. Nagayama, Chemcial Physics Letters 1995 462-468.
7
Deegan, R. D.; Bakajin, O.; Dupont T. F.; Huber, G.; Nagel, S. R.; Witten, T. A. Nature 1997, 389, 827.
8
Robert D. Deegan, Olgica Bakajin, Todd F. Dupont, Greg Huber, Sidney R. Nagel, and Thomas A. Witten. “Contact line deposits in an evaporating drop.”
July 2000. Physical Review. P756-765.