Homework/Test questions Name: 1.Read the lecture on nanotechnology by R.P. Feynmann, "There's Plenty...

Homework/Test questions Name:

1.Read the lecture on nanotechnology by R.P. Feynmann, "There's Plenty of Room at the Bottom": http://www.zyvex.com/nanotech/feynman.html

Provide Answers:

What does he mean by shadow it by evaporating gold at an angle. Hand draw a picture.

What did he propose to make copies of the master? Hand draw a picture of what you understand he suggested.


• What is described by the following equation:

• What does n, stand for.

• Describe how the two pictures below impact the resolution.

• Describe how the two pictures below impact the depths of focus.

Optical Microscopy


• what are the elements of an SEM?

• how does the electron gun work?

• what is the acceleration voltage?

• what happens if electron impact on the surface?

• what signals can you record and where would you place the detector?

• What is the primary reason which limits the resolution of an SEM?

• Name three different signals that you can record, the primary application of the three signals, and the anticipated resolution in each case.


Consider three signals

Elastically Scattered

Secondary

X rays

Where do you place the detector and how effective is the use of an external bias?


• Draw the process of Auger electron emission?

• Describe the process:

step 2:

electron vacancy

KKL1

L23

Sea of valence electrons

1s

2p

2s

electron vacancy

KK

L23


1s

2p

2s

electron vacancy

KKL1

L23


1s

2p

2s

initial state step 1:


• Draw the process of X-Ray emission?

• Describe the process:

step 2:

electron vacancy

KKL1

L23


1s

2p

2s

electron vacancy

KK

L23


1s

2p

2s

electron vacancy

KKL1

L23


1s

2p

2s

initial state step 1:


• Draw the process of Auger electron emission, what is the energy in eV?

• Draw the process of X-Ray emission

what is the energy in eV?

• Label the axis of an EDS spectra.

• What is an ionizing process?


• Label the axis of an EDS spectra.

• What is an ionizing process?


• Following a K shell excitation, the energies of the emitted characteristic X-ray and the equivalent emitted Auger electron are slightly different. Complete the equation:

• Exray = ( EK - ) • Eauger = ( EK - )


What instrument is shown?

Describe it’s use.

Label what is plotted along the x and y axis.

Describe the detection process how do you get the counts and energy levels. Begin like this: The sample is illuminated and emits distinct X rays at different points in time.

detected

voltag

e 1

detected

voltag

e 2

x

y


Name two scanning probe instruments.

Select one and draw the basic elements that form the system. Label all the necessary physical modules and parts that are involved in the feedback loop.


What you should know?Test Questions:

Select one -- an AFM or STM and draw the basic elements that form the system. Label all the necessary physical modules and parts that are involved in the feedback loop. Describe in you own words how the feedback loop works if the instruments scans over the surface and encounters a positive step in the topography. Begin with the cause: A positive step height will increase/decrease the xxx. The xxx will ......yyy. The yyy will ...zzz. The zzz will..... mmm. The mmm will....


What you should know?Test Questions:

2

2m

d2(x)

dx 2E(x)

Given the Schrödinger equation. Pick a solution and demonstrate that this solution fulfills the equation and boundary conditions of an electron in a box.

Draw the wave function inside the box for the first two lowest possible energy levels.

Draw the probability function inside the box for the second lowest possible energy levels. Where is the probability zero?

Use your solution and derive the following equation:

E n2(2 2

2mL2)


For tunneling to occur - (A) the wavefunctions of both surfaces have to be complementary,(B) the wavefunctions of both surfaces have to overlap(C) the wavefunctions of both surfaces have to be complex(D) the surface require a small workfunction (E) the surface require a large workfunction (F) a larger workfunction requires a smaller separation for tunneling to occur.(F) a larger workfunction requires a larger separation for tunneling to occur.


• Write down an equation that describes how the tunneling current between two metal surfaces depends on the distance between two surfaces. I = Io * .........

• There is a characteristic unit K how big is this typically for most materials: (A) K=1/(.1 nm) , (B) 1/(10 nm), (C)1/(1000nm)?

• If you increase the distance by a factor of 10, derive an equation that tells you how big a change in the current you will get considering tunneling?


• Transfer function of the AFM• Each arrow can be represented by a transfer function some of which

are linear while others are none linear. • Derive the transfer function that describe the behavior of the AFM tip

G1(f)=Z(f)/F(f). Considering your transfer function how would you choose spring constant and mass.

Homework/Test questions Name:Notes from lecture if you did not write this down.


Derive and complete the following equation for an AFM that operates using the optical deflection method. Begin your solution with a mechanical illustration that contains the physically relevant elements:

l

l....... shift Beam

CANTILEVER

................-.........TIP


V1V2

You load a contact mode cantilever into an AFMPick the one with the highest sensitivity in the figure on the right:The detector in your AFM is 5 cm away from your tip. The diameter of you laser beam is 1 mm and lined up at the intersection between the top half and bottom half of the detector. V1 and V2 read 5 V each. Calculate the force that is needed to reduce the voltage V1 to zero.

200 um

200 um100 um

100 um

Write down your answer here:

l

l2z shift Beam

CANTILEVER

Detector-TIP


• Write down 4 different forces that can be detected between an AFM tip and a substrate. The AFM tip has a tip radius of 20 nm.

- (1) ........

- (2) ........

- (3) ........

- (4) ........

• Complete the sentence: With the exception of ............. these forces are typically in the ... N (select: fN, nN, pN, mN, N) range.

• In the force distance curves that we have taken one force did dominate. Which one? ....

• Write down one equation that can be used to estimate a force.


• Describe the basic function of How and Atomic Force Microscope can be used to measure the Electric Surface Potential Distribution? Consider the concept of feedback. There is a need for a closed loop control system to get quantitative values of the surface potential. Draw and label the parts that are required including, mechanical, optical, and electrical elements to form the particular closed loop system whereby the output signal is the surface potential. Clearly label the location where you would monitor the surface potential.


• Draw a force distance curve that you would expect to record with an AFM in air at ambient pressure and humidity.

• Label the axis

• Label a regions where the total force is attractive.

• Label a region where the total forces is repulsive.

• Name two attractive =

• and one repulsive force =

• that you know.

Added:


• Optical LithographyDo you want a small or large depths of focus? and why?

Describe the interplay between minimum feature size and depths of focus and why it is problematic in lithography?

(a) Use equations to help your arguments

(b) Use a drawing to show that a small NA increases the depths of focus.


Which electron cause most damage (loose energy)?

Backscattered or Secondary?

What resolution do you expect?

10 nm, 100 nm, 1 um

How could the film thickness effect the resolution?

Why is the resolution limited of an ebeam writer and not equal to half the wavelength of an electron?


• Name three top down Micro/Nanofabrication methods?

• Write down what limits the resolution in each cases?

• Write down the minimal line width that you expect?

• Classify the throughput using parallel (fast) and serial (slow)?

• Which once are available to small companies?


Optical Lithography

• Deep UV Lithography in the 157-193 nm range is challenging because the optics/lense is..

• Extreme UV requires the use of re………… optics.


Derive an equation to show that the smallest pitch in interference lithography is equal to half the effective wavelength. Begin with the

equations for two traveling waves.

tjjkzeAeztHE ),(, tjjkzeAeztHE ),(,

22 )()(Re tjjkzjkz AeeeINTENSITY

tjkzjkzj eeeConstINTENSITY 222 )(21Re*


inte

nsity

0

)2cos()2cos(1*),( tkzItzINTENSITY

plot the intensity

)2cos(1*)( kzConstzINTENSITY

What is the center to center distance between exposed lines (pitch) for 300 nm light = 150 nm

What is the widths of the photoresist features that you

expect for 300 nm light ~70 nm


Spin coating

• What do you think controls the film thickness?

- spin speed

- viscosity of the solution

- and solvent to polymer mass ratio

connected

• What could you do to increase the thickness of the spin-coated layer 10 times?


• (a) What is done to in projection lithography to reduce the feature size?

• (b) What is the technological challenge following the path outlined in (a)?

• (c) Which part 1-6 needs to be replaced first.

• (d) Describe the replacement part that will enable a continuation of projection lithography


Vacuum deposition

• Describe why deposition rate is a function of pressure? Find a gas kinetic equation to justify your arguments.

Homework/Test questions Name: added:

• Why is the deposition rate slow and control large when you go to high vacuum systems.

• Write down an equation that relates the volume number concentration with the pressure.


e=1.6 10-19 C750 Torr = 0.98 atm = 1 bar = 105 Pa = 105 N/m²

• Given is a vacuum system that you evacuated to 10^-7 Torr. • After heating a gold pellet the pressure increases to 10^-6 Torr

where it stabilizes.• Estimate the Au atom volume concentration.

• What is the average spacing between the gold atoms?

n = 3.3 1016 /m3

spacing = 3.1 um


Exercise: Calculate n at 1 bar and average spacing between molecules

1 bar = 105 Pa = 105 N/m² = n kT

kT= 25 meV=25 mV*1.6 10-19 C

n = 2.5 1025 /m3

spacing = 3.4 nm

750 Torr = 0.98 atm = 1 bar = 105 Pa = 105 N/m²

Pressure and Particle per volume

Exercise: Repeat at high vacuum 10-12 bar

n = 2.5 1013 /m3

spacing = 30 um

added:


• What is the equilibrium vapor pressure of silver at 1200 degC?

• Under equilibrium pressure of silver at 1200 degC what is the volume number concentration in 1 m3 and the combined weigth of all the atoms in this volume in nano grams?

x ng


Evaporation Rate

Consider a evaporator that is pumped down to 10-10 torr.It holds a 10 mm in diameter gold pellet that is heated to 1600 degCCalculate the evaporation rate in the initial stage.


Nanoxerography• The figure on the right shows the

concept of a nanoxerographic printer.

• It uses a tube furnace to create nanoparticles by evaporation and condensation.

• Atoms are carried out by the carrier gas and condense into droplets and solid particle downstream.

• How this works: Vapors are produced by evaporation at temperatures implying a significant vapor pressure; the cooling triggers supersaturation by reducing the saturation vapor pressure and leads to nano-particles with the same composition than the initial liquid or solid material. (Homework question on next page)Good review article on Nanoparticle aerosols:

http://www.iop.org/EJ/abstract/0022-3727/39/2/R01/

1atm-13

1 atm

13

ord

ers

of

ma

gn

itude

diff

ere

nce

in

pa

rtia

l pre

ssu

re

gold


e=1.6 10-19 C750 Torr = 0.98 atm = 1 bar = 105 Pa = 105 N/m²

• Look up the partial vapor pressure of gold at the given temperatures and make first order estimates of the number of gold atoms that you have in your tube. The tube volume is 100 cm3

10^-8atm => 2.5 10^17 / m3 25E12

10^-4atm => 2.5 10^21 / m3

• Next you purge the tube with the carrier gas (exchanging the entire volume). The atoms in the 100 cm3 will condense into nanoparticles. The size distribution is not uniform. However, lets assume that all particles contain 106 atoms and can all be collected on a 1 x 1 cm2 substrate. What is the average interparticle distance on the surface?

• Do you expect more than one particle layer?

n (1050) = 25 1012

spacing (1050) = 63 nm

A tube furnace containing a gold pellet has been purged with nitrogen. The flow has been stopped and the temperature has

been increased to 1050 degC. (repeat for 1550degC)The system is at atmospheric pressure.

n (1550)= 25 1016

spacing (1550) = 0.0063 nm


04/21/23 39

Unconventional Nanotechnology & Nanopatterning (~2 lectures)

Scanning Probe Lithography,

Soft-Lithography & Nanoimprint


• Draw a conceptual picture of an Electric Scanning Probe Lithographic Instrument.

• Describe how it works?

• What instrument would you modify?

• Name one major limitation.



Understand the basic function of an electric scanning probe lithography ESPL instruments and draw a picture of an ESPL showing the basic elements (label at least 6 elements that are essential to pattern a surface).

Can and Atomic Force Microscope be converted? and if yes what is needed for the conversion to work?

Can an STM Microscope be converted to expose and electron beam sensitive resist? and if yes what is needed for the conversion to work?

What is the difference in the feedback to operate an AFM when compared to an STM?

What does this mean for the samples?


H+

OH- OH-H+

water meniscusyou have modified an atomic force microscope by connecting an electrical lead to apply a voltage bias to the semiconducting AFM tip. The sample is titanium and you would like to form titanium oxide underneath

the tip.

Do you need to apply a positive or negative potential to the tip with respect to the sample to oxidize the

sample?

Do you expect that all metals can be oxidized?

Are the voltages going to be different

what is a minimal voltage that you expect using a first order estimate and looking at: http://en.wikipedia.org/wiki/Table_of_standard_electrode_potentials


Exposure of Electron Sensitive Resists.

You have modified and AFM to expose "e-beam" sensitive resists.

What is the price of such an instrument?........ $

AFMs cost ~300k,SEMs cost > 1M.

What resolution (line widths) do you expect based on previous results (see results)?........

What is the throughput in time per cm2 sized area? ........

Hint: Maximum line speeds today are ~ 100 um/s. Assume that you were to try to expose the entire surface of a cm2 sized area with a single tip/beam.

How does the throughput compare with traditional single cell e-beam lithographic systems? ........


Explain how KFM can measure the local surface potential by filling in appropriate words:

KFM detects localized ................ forces between the tip and the sample to measure the surface potential of the sample. A .................... is used to adjust the ..... tip ................. until the ............... force ........... At this point the DC tip ................ is equal to the local surface ............


Name two physical effects that will cause a variation in the surface potential?

How do you record charge patterns and surface potentials

without touching the sample?

KFM Kelvin Probe Force Microscopy --- A quick excurse to a special AFM to map electrical

charges and potentials


You have IC circuit structure that contains a number of different materials with different electron affinities. The structure has a Al, Au, and Si regions as illustrated.

AlAu

top view

AuAu

Au

side view

Au

ElementWork Function(eV)

Aluminum 4.08

Beryllium 5.0

Cadmium 4.07

Calcium 2.9

Carbon 4.81

Cesium 2.1

Cobalt 5.0

Copper 4.7

Gold 5.1

Iron 4.5

Lead 4.14

Magnesium 3.68

Mercury 4.5

Nickel 5.01

Niobium 4.3

Potassium 2.3

Platinum 6.35

Selenium 5.11

Silver 4.73

Sodium 2.28

Uranium 3.6

Zinc 4.3

Si 4.52eV

Si


Questions:

Is there a electrostatic potential difference between the different regions even if you do not apply an external bias to the films? YES/NO

If YES which material is most positive? (Au, Al, Si)

which film is most negative? (Au, Al, Si)

which is in the center? (Au, Al, Si)

What is the potential difference between the Au and the Al?

I indicated a 1 um in diameter half circle. Would you expect an electrostatic field along this line?

YES/NO

If YES how big would this field be?

E= ... V / m


Surface Charge Double Layer Relationship.

Given is the picture with an insulating charged layer that is 100 nm thick and charged to 100 elementary charges per 100 nm x 100 nm area. The layer extends in x-y direction. The

charge sits on an insulator with r = 15. Underneath the insulator is a gold film.

Questions:Is the picture missing image charges in the gold substrate? (YES/NO)The field above the surface at location 1 and 2 is constant/not-constant?The field above the surface at location 1 and 2 is zero/non-zero? The field inside the insulator at location 3 is zero/non-zero? The field inside the conductor at location 4 is zero/non-zero? Calculate the potential drop that is caused by the surface charge? delta V = ........ VoltsImagine an AFM tip above the surface. What potential do you need to apply to the tip to null out the attractive force? ......... Volts. You now replace the substrate with a semiconductor. Do you expect a larger or smaller voltage for the same amount of charge?

++++++++++++++++++++++++++++++++++++++++++++++++++++++

1

2

3

4


Soft Lithgraphy

• Name two primary reasons why soft lithographic tools are being used? Hint: Compare with scanning probe lithography, compare with projection lithography..

• - How do you fabricate a mold? < Three sentences- How is a PDMS stamp made? < Three sentences

• - Describe the key steps on how to print a self-assembled monolayer (SAM) using a PDMS stamp?

• - How do you check if you succeeded in printing a SAM with -COOH or -CH3 end groups ?

• -You have made an e-beam pattern in PMMA and would like to make a replica without going back to the e-beam writer. Describe a two step process that gets you a replica in PMMA < Three sentences


• Why is the resolution limited in Soft-Lithography?

• Describe the concept of Phaseshift Photolithography


Pervious Slides include the Material up to First Midterm


• L11


Write down 5 different physical properties that change and a reason why other than size.


Write down the primary reason why the crystal lattice constant becomes

smaller.


Nanomaterials demonstrate decreased conductivity with

decreasing size due to _____ as well as increased

conductivity with decreasing size due to ______.

Added DEC 2010


If you keep cutting you increase/reduce the

overall surface free energy and Gibbs free energy by reducing/increasing

the number of free bonds.

Did you create free radical surface groups? No/Yes

Does the stored energy go up? Yes/No

Does this relate to powder explosives? Yes/No

Do you expect surface reconstructions over time? Yes/No

Will this increase the free energy? Yes/No

Correct the sentence

Does this have an effect on the melting

point as you go to nanoparticles? NO/Yes

Does this have an effect on the lattice

constant as you go to nanoparticles? NO/Yes


Self-Assembled Monolayers can Change the Surface Free Energy.

A nanocrystal has been passivated and the surface free energy has been reduced. Do you expect it to be under reduced "compression"?

What do you expect in terms of lattice constant?


Name the primary two reasons for an increased hardness in the case of nanowiskers?


Note: There is an important difference in the Lorenz oscillator model between metals and insulators.

Which statements are correct?

The adsorption for metal and insulators is a function of frequency? (yes/no)

The transmissivity for metal and insulators is a function of frequency? (yes/no)

The refectivity for metal and insulators is a function of frequency? (yes/no)

The "spring constant C" in the lorenz oscillator model for bulk metals is assumed to be zero because there is not restoring force? (yes/no)

The damping in bulk metal is due to elastic scattering? (yes/no)

The damping in bulk metal is due to inelastic scattering? (yes/no)

For insulators we can define a resonance frequency 0? (yes/no)

The resonance frequency 0 in insulators is close to a maximum adsorption? (yes/no)

0 is zero in bulk metals.

There are four distinctive regions in metals referred to as TART and two in insulators referred to as RT.

The transition between RT occurs at the plasmon resonance in metals

Relaxation time


Note: Read the text marked as "additional reading" to answer the following questions.

Describe why the widths of the resonance is increased with decreasing particle size.

Will the scattering be increased and why as you reduce the particle size.

The MIE theory describes the oscillation modes of a spherical metal particle in an insulating matrix and is based on Maxwells equation. (yes/no)

It does not account for the size dependence in the adsorption that is observed for metal nanoparticles unless is modified to account for increased scattering effects. (yes/no)

Relaxation time


Which electron configuration has a higher Energy?

- -+ +- -+ +

Which energy curve belongs to which orbital?

H2 Molecular Wavefunctions


Use the picture on the right to describe why energy splitting

of orbital's causes an increased bandgap as you

reduce the crystal size.

Use the particle in a box picture on the right to make a similar case and write down a

mathematical function L.


• L15


Element

Fermi Energy

eV

Fermi Velocityx 10^6

m/sLi 4.74 1.29Na 3.24 1.07K 2.12 0.86

Rb 1.85 0.81Cs 1.59 0.75Cu 7.00 1.57Ag 5.49 1.39Au 5.53 1.40Be 14.3 2.25Mg 7.08 1.58Ca 4.69 1.28Sr 3.93 1.18Ba 3.64 1.13Nb 5.32 1.37Fe 11.1 1.98Mn 10.9 1.96Zn 9.47 1.83Cd 7.47 1.62Hg 7.13 1.58Al 11.7 2.03Ga 10.4 1.92In 8.63 1.74Tl 8.15 1.69Sn 10.2 1.90

Pb 9.47 1.83

Bi 9.90 1.87

Sb 10.9 1.96

2

1F

mv

ne d

How big is the Characteristic Scattering Distance in Gold?

Calculate d

The measured conductivity of gold at 20°C is

45* 106


How big is the Effective Scattering Distance of Cobalt at Room temperature for the three different films?

Why does the resistivity reduce approximately proportionally with

temperature?

Element

Fermi Energy

eV

Fermi Velocityx 10^6

m/sLi 4.74 1.29Na 3.24 1.07K 2.12 0.86

Rb 1.85 0.81Cs 1.59 0.75Cu 7.00 1.57Ag 5.49 1.39Au 5.53 1.40Be 14.3 2.25Mg 7.08 1.58Ca 4.69 1.28Sr 3.93 1.18Ba 3.64 1.13Nb 5.32 1.37Fe 11.1 1.98Mn 10.9 1.96Zn 9.47 1.83Cd 7.47 1.62Hg 7.13 1.58Al 11.7 2.03Ga 10.4 1.92In 8.63 1.74Tl 8.15 1.69Sn 10.2 1.90

Pb 9.47 1.83

Bi 9.90 1.87

Sb 10.9 1.96

2

1F

mv

ne d

The figure illustrates the electrical resistivities of Co thin films 110 nm, 20 nm and 12.5 nm thick

Why do you see an increase in the resistivity as you reduce the film

thickness?


• For ballistic transport to occur the physical device dimensions have to be smaller/larger (cancel) than the electron mean free path.

• Write down an simple equation that relates the potential drop (E = V) with the gained velocity considering ballistic transport without any scattering.

added:


Describe a mechanism by which semiconducting nanowires can become insulating as you shrink down the size.


• L17


Why do nanoparticles or wires show distinct crystal facets?

Do these facets represent an energy minimum? Yes/No

Do you expect them to have a larger number of dangling bonds than other configurations that are less likely? Yes/No

Will all nanomaterials form facets? Yes/No, Explain.


Describe what happens when you increase your solute concentration over the equilibrium concentration of your solute?

Describe the concept of Oswald Ripening -- what happens to the embryos and what happens to the nuclei and what happens to the

solute concentration?


Describe how you can prevent agglomeration through charge stabilization: (a few sentences) What are the parameter that you

can adjust?

Is it good to be working at the P.Z.C point? Yes/NoWould you like to have a large Surface Potential? Yes/NoIs a larger double layer thickness advantageous? Yes/No

Would you like to have a large or small counter ion concentration? Large/small


Describe how gold nanoparticles were used as a NaCl sensor.

What happens to the nanoparticles as you increase the NaCl concentration and why?

What is the change that you observe with your eye and why?

added:


Local heat generation resulting from plasmon resonance in metallic nanoparticles can be used as efficient heat sources for biological and oncological purposes. If a variety of different illumination sources are to be considered, which particle geometry would be best suited to provide the most versatility: spheres or shells. Why?

Added DEC 2010


• Taking into account the model of a 1-D energy band, which polyacetylene electron configuration represents the HOMO and LUMO?

Added DEC 2010


• Assume Si is at room temperature. Circle where the lowest possible energy holes are located in the valence band.

Added DEC 2010


• At what size will quantum size effects occur for a nanocrystal?

• At this size, a particle is transitioning between which two electron state regimes?

Added DEC 2010


• Find which sizes of Al, GaAs, and GaAs(2D) at which quantum size effects occur

• Will conductivity increase or decrease when shrinking to these sizes?

Added DEC 2010


• Describe the mechanisms of thermal and defect resistivity and how they related to the total resistivity of a material

Added DEC 2010


In ballistic transport:• Electrons have so much energy, they must dissipate

some of it as heat (True/False)• There cannot be impurities present (True/False)• Elastic and not inelastic scattering is observed

(True/False)• Device dimensions are less that the electron mean free

path (True/False)• Very high current densities can be observed (True/False)

Added DEC 2010


• If ΔG* is not provided to a homogeneous nucleation experiment (ΔG< ΔG*), describe how dissolution or precipitation drive particle growth

Added DEC 2010


• Describe a method for fabricating flexible electrodes with low bend radii on PDMS

Added DEC 2010


• Describe how peel rate can be used to control pickup vs printing modes during transfer printing

• Describe alternate methods for controling pickup vs printing modes

Added DEC 2010


• L21


• Nanoxerographic printing from a powder has a limited resolution. Name the primary reason why the resolution is limited. Hint the reason are has to do with the particles.

• Consider Iron Oxide as a primary particle. Is the surface hydrophobic?

• TEM studies have shown that the primary particle size is 10 nm. What will happen to particles in a powder form and

why?



• Nanoxerographic printing in a liquid has a limited resolution. Name the primary reason why the resolution is limited. Hint the reason has to do with the particles.

• The assembly works only in non-polar solvents. Describe why?

• Based on previous lectures what happens in water (remember water contains H+ and OH-) to the electric field. What was a typical screening length? 10 nm or 10 um choose one.

• You have learned methods to prevent particle aggregation in solution will they work in this case?

• How about using a non-polar polymer brush surrounding the particles?



• L22


weak and strong interactions between neutrons and protons

gravitational forces

ionic&covalent&hydrogen bonds

Van-de-Waals forces

magnetic forces

ionic&covalent&hydrogen bonds,

coulomb forces,

Hydrophobic/hydrophilic interaction,

capillary forces,

surface tension

drag force

Review the coursework material and identify forces that can be neglected in the design of self-assembly processes. Consider all length scales (1nm-1mm). Cancel out the identified forces in the list:

Brownian motion


How strong is the interaction? To answer this questions assign a single letter A,B,C,D for the strength in ordering energy as multiples of kT (T= room temperature) the best describes the situation:

Group A: 1kTGroup B: <10 KT

Group C: 1-400 kT Group D: 0-10...0kT

gravitational forcescovalent bond & ionic bondhydrogen bonds

Van-de-Waals forcesmagnetic forces

coulomb forces,

Hydrophobic/hydrophilic interaction,

capillary forces,

surface tension

drag forcebrownian motion

Group: ..

Group: .. Group: ..

Group: .. Group: ..

Group: .. Group: ..

Group: .. Group: ..

Group: .. Group: ..

1 point1 point

1 point

1 point1 point

1 point

1 point1 point

1 point1 point

1 point


What is the typical range in terms of length scales of the interactions? To answer this questions assign a single letter A,B,C,D that best describes the situation:

Group A: short range < 1 nm Group B: intermediate range < 10nm Group C: long range > 100 nm

Group D: All ranges (nano, micro, macro)

gravitational forcescovalent bond & ionic bondhydrogen bonds

Van-de-Waals forcesmagnetic forces between macroscopic or nanoscopic objects

coulomb forces between macroscopic or nanoscopic objects,

Hydrophobic/hydrophilic interaction, (will not be graded, note occurs upon contact)

capillary forces, (will not be graded, note occurs upon contact)

surface tension (will not be graded, note occurs upon contact)

Group:

Group: Group:

Group:

Group:

Group:

Group:

Group: Group:

1 point1 point1 point

1 point1 point

1 point


Describe three different concepts to integrate Nanoparticles in addressable regions on a surface?


Describe a technology that allows you to integrate a Nanowires at precise locations on a surface. The technology should allow to both control the location and diameter of the nanowire.


Describe a technology that allows you to control the in plane orientation of nanowires.

How do you fabricate crossed wire arrays?


Considering the Scaling Laws. What do you think is the expected range for surface tension directed self-assembly processes?

Hint:at what approximate scales will gravity matter?

at what approximate scales will Brownian motion matter?

Can you eliminate gravity?

Can you eliminate electrostatic forces in your experiment? If yes how?

Can you eliminate drag forces in your experiment? If yes how?

Homework/Test questions Name: Homework/Test questions Name:

The opening in your resist structure is 1 um in diameter

Your particle holds a single elementary charge.

and the potential difference measure by KFM is 1 V.

How big is the uncertainty in precision? (Theory)

Looking at the equation What determines the uncertainty?


Consider a 10 nm sized Silicon particle in Air

1. What is an approximate value for the diffusing coefficient?

2. Find the density of Silicon online

3. Calculate the characteristic frequency.

4. The particle holds 1 elementary charge. At time 0 you turn on an electrostatic field 1V/1m in x direction. -- What is the drift velocity? -- How many seconds does it take to reach 63.2% of its terminal velocity -- Considering this time how far has the particle moved.

5. Now you turn off the x component of the field -- How many nanometers will the particle continue to move in x directions

6. considering these calculations do you think that the particle will follow field lines with close proximity (Yes/No)

characteristic frequency:kT

mD


Ef,y

∆x=radius of curvature=stopping distance

Vo,x

•The ability for a nanoparticle to follow a given field line is described by the radius of curvature.

•This is generated as the nanoparticle dissipates and absorbs energy per cartesian axis.

•The more charge a nanoparticle has, the faster will it react to an incoming electric field.

Nanoparticle Assembly Radius of Curvature (Theory)

Write down a simple equation for the stopping distance that contains two variables

Homework/Test questions Name: 1.Read the lecture on nanotechnology by R.P. Feynmann, "There's Plenty...

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