Micro and Nanomechanics LabDepartment of Mechanical Engineering
Science and Technology of Science and Technology of UltrananocrystallineUltrananocrystallineDiamond Films for Multifunctional MEMS/NEMSDiamond Films for Multifunctional MEMS/NEMS
H.D. Espinosa
Acknowledgments: NSF-NIRT
U.S. – South America Workshop:Mechanics and Advanced Materials Research and Education
Rio De Janeiro, Brazil, August 2-6, 2004
Micro and Nanomechanics LabDepartment of Mechanical Engineering
OutlineOutlineNIRT Project OverviewFilm Deposition and CharacterizationIdentification of Mechanical PropertiesMultiscale Modeling starting from Quantum MechanicsApplications:
AFM PotentiometryMolecular Writing and Self AssemblyNEMS, e.g., nanoresonators
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Participating Institutions/OverviewParticipating Institutions/Overview
Micro and Nanomechanics LabDepartment of Mechanical Engineering
UltrananocrystallineUltrananocrystalline Diamond Films For Diamond Films For Multifunctional MEMS/NEMS DevicesMultifunctional MEMS/NEMS Devices
Why UNCD?H.D. Espinosa, Z. Chen, T. Belytschko, M. Hersam, G. Schatz, O. Auciello and M. Moldovan
Extremely high wear resistant (10,000 times longer than Si)
Very low friction coefficient (0.03-0.04 in air)
Very resistant to chemical corrosion
Low threshold, stable field electron emission (~2-3 V/µm)
Broad optical transparency
Highest thermal conductivity (2 x 103 W/m/ K)
Very high elastic modulus (965 GPa)Extreme mechanical hardness (~97 GPa)
Applications
Massively parallel AFM potentiometry
Nanoresonators• Mass Sensors• Wireless Communication• Bio-sensors• …
ραϖ
12
2 EtL
=
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Film DepositionFilm DepositionOrlando Orlando AucielloAuciello and John Carlisle (ANL)and John Carlisle (ANL)
Micro and Nanomechanics LabDepartment of Mechanical Engineering
iPlasiPlas Microwave Plasma CVD System at ANLMicrowave Plasma CVD System at ANL
OES of Ar/CH4 Plasma
200 400 600 800 1000 1200
C2- Main species forthe growth of UNCD
C2 emission
Inte
nsity
(a.u
.)Wavelength (nm)
Typical Ar/CH4 Plasma
2CH4 → C2H2 +3H2
C2H2 → C2 + H2
CH4 + Ar + H2 = 100 sccm
CH4 = 1 sccm; Ar = 95-99 sccm
100 Torr; 1200 WUNCD Growth Rate:0.15 ~ 0.2 µm/hr (400oC)0.25 ~ 0.3 µm/hr (800oC)
D. Gruen, “Nanocrystalline Diamond Films,” Annu. Rev. Mater. Sci., Vol. 29, pp. 211-259, (1999).
Seeding
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Grain Size vs. Grain Size vs. ArAr RatioRatio
Grain size as a function of the Ar ratio: (a) 40%, (b) 60%, (c) 97%, (d) 99%.
D. Zhou et. al., J. Appl. Phys., Vol. 84, pp 1981-1989, (1998).
Raman Spectra shows the Raman Spectra shows the diamond band is broadeneddiamond band is broadened
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Grain Size vs. NGrain Size vs. N22 RatioRatio
(a) 0% N(a) 0% N22 UNCD, (b) 5% NUNCD, (b) 5% N22 UNCD, (c) 10% NUNCD, (c) 10% N22 UNCD, (d) 20% NUNCD, (d) 20% N22UNCD. Grain size increase from 4 to 16 nm; grain boundary width UNCD. Grain size increase from 4 to 16 nm; grain boundary width increases from 0.5 to 2.2 nm. Nincreases from 0.5 to 2.2 nm. N22 is incorporated preferentially at the is incorporated preferentially at the grain boundaries.grain boundaries.
Grain + Grain boundary morphologyGrain + Grain boundary morphology
J. J. BirrellBirrell et al., App. Phys. Let., Vol. 81, pp. 2235et al., App. Phys. Let., Vol. 81, pp. 2235--2237, 2002.2237, 2002.
Micro and Nanomechanics LabDepartment of Mechanical Engineering
100 nm
Super GrainsSuper Grains
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Scanning Probe Microscopy Characterization of Scanning Probe Microscopy Characterization of UNCDUNCD
Effect of Substrate: Si vs. W/Si(Top Surface)
(a) (b)
(a) Topside of an undoped UNCD film on a Si substrate with roughness of 20 nm. (b) Topside of an undoped UNCD film on a W/Si substrate with roughness of 14 nm.
M. Hersam’s group
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Scanning Probe Microscopy Characterization of Scanning Probe Microscopy Characterization of UNCD (UNCD (con’tcon’t))
Effect of Substrate: Si vs. W/Si(Bottom Surface)
(a) Backside of an undoped UNCD film on a Si substrate with roughness of 3 nm. (b) Backside of an undoped UNCD film on a W/Si substrate with roughness of 1 nm.
(a) (b)
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Contact Mode AFM MeasurementsContact Mode AFM Measurements
Initial cAFM Data(Undoped vs. N2 Doped UNCD)
0
2E-11
4E-11
6E-11
8E-11
1E-10
1.2E-10
0 2 4 6 8 10 12
Voltage (V)
Curr
ent (
A)
UpsweepDownsweep
0.E+00
1.E-09
2.E-09
3.E-09
4.E-09
5.E-09
6.E-09
7.E-09
8.E-09
9.E-09
0 2 4 6 8 10 12
Voltage (V)Cu
rren
t (A)
UpsweepDownsweep
Undoped: R ~ 50 GΩ 10% N-Doped: R ~ 0.3 GΩ
cAFM I-V spectroscopy taken with a Pt coated tip
M. Hersam’s group
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Mechanical TestingMechanical Testing•• ModulusModulus•• StrengthStrength•• Fracture ToughnessFracture Toughness
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Wafer Level MicroWafer Level Micro--scale Tension Testscale Tension Test
Membrane Deflection Experiment (MDE)-Use Nanoindenter to stretch membrane-Obtain load-deflection response and stress-strain curve, extract E, σr and σf
-Fracture Toughness, KIC
H.D. Espinosa et al., J. Mech. Phys. Sol., Vol. 51, pp. 47-67, 2003
Gauge AreaLine-load Tip Membrane
InterferometricObjective
Micro and Nanomechanics LabDepartment of Mechanical Engineering
UNCD MDE SpecimensUNCD MDE Specimens
20 µm
Non-uniformities due to wafer seeding process
200 µm
4” wafer
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Fabrication StepsFabrication Steps
Si substrate <100>(a)
(b)
(c)
(d)
Si3N4
UNCD
Al film
Etch Si (wet)
Etch UNCD (RIE)
Etch Si3N4 (RIE)
Fabrication steps on <100> Si wafers:(a) Deposition of UNCD film followed by Al film deposition(b) Wet etching of Al to define the pattern of UNCD(c) Dry etching of Si3N4 followed by wet etching of Si(d) Dry etching of UNCD (O2 plasma), removing the Al film
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Stress CalculationsStress Calculations
PV
Wafer
MirauMicroscopeObjective
PMPMθ
LM
∆
)sin(2)()(θ
σm
V
AtPt =
Am = membrane cross-sectional area
PV(t) = load at time t
σ(τ) = Stress at time t
Cauchy Stress
Combined AFM/Nanoindenter with Integrated Mirau Microscope-Interferometer
H.D. Espinosa et al. J. Mech. Phys. Sol., Vol. 51, No. 1, pp. 47-67, 2003
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Strain CalculationsStrain Calculations
λ = wavelength of interferometer light.
δ = distance between fringes
ε(t) = Strain at time t
Strain
1)2/(
)(22
−+
=δλδ
ε t
θ1
Fringes(c)
3λ/4 λ/2 λ/4λ/2
δ
Fringes
Bottom surface of membrane
Micro and Nanomechanics LabDepartment of Mechanical Engineering
StessStess--Strain CurvesStrain Curves
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.0045
Strain
Stress (MPa)
Undoped
5% Nitrogen
10% Nitrogen
20% Nitrogen
σσf1 f1 = 4.17 = 4.17 GPaGPa
σσf2 f2 = 2.71 = 2.71 GPaGPa
σσf3 f3 = 2.45 = 2.45 GPaGPa
σσf4 f4 = 2.35 = 2.35 GPaGPa
The stress at 63% failure probability
23502350244624462713271341724172σσ00 ((MPaMPa))
833833--865865854854--880880878878--921921940940--970970E (E (GPaGPa))
3030303030303030No. of testsNo. of tests
20%20%10%10%5%5%0%0%NN22 percentagepercentage
DopedDopedUndopedUndopedSampleSample
Micro and Nanomechanics LabDepartment of Mechanical Engineering
200200400800Side Wall Area (µm2)
12008200840032800Total Surface Area (µm2)
5002000400016000Volume (µm3)
10.511Thickness (µm)
5202040Width (µm)
100200200400Length (µm)
DCBASamples
undopedundoped B. Peng et al., submitted to J. Appl. Phys., 2004
−−=
mWeibullf V
VP0
max
0
exp1σσ
NiPf
2/1exp −=
−−=
mWeibullf A
AP0
max
0
exp1σσ
Size Effect Size Effect –– Applicability of Applicability of Weibull Weibull TheoryTheory
Micro and Nanomechanics LabDepartment of Mechanical Engineering
WeibullWeibull TwoTwo--parameter Modelparameter Model
or
−−= e
m
Vf VP )(exp1
0
max
σσ
−−= e
m
Af AP )(exp1
0
max
σσ
6.5
7.5
8.5
9.5
10.5
11.5
0.5 1.5 2.5 3.5
Scaling Parameters
Cha
ract
eris
tic S
tren
gths
( σ0V
or σ
0V)
Size ASize BSize CSize D
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
2500 3500 4500 5500
Failure Stress (MPa)
Prob
abili
ty o
f Fai
lure
Sample C
Volume
Total Surface Area
Side wall Area
Volume Surface Sidewall
Estimate the two Weibull parameters, σ0v/σ0A and m, by nonlinear regression
Volume was found to be the control factor m = 11.6, σ0V = 8581 MPa×µm3/m
Micro and Nanomechanics LabDepartment of Mechanical Engineering
FractographicFractographic Analysis (Analysis (undopedundoped))
2 µm
Grain nucleation layer
Top surface
Cluster of grains
Intergrannular FracturePolysilicon
W.N. Sharpe et al., J. MEMS, Vol. 12, 2003
Micro and Nanomechanics LabDepartment of Mechanical Engineering
FractographicFractographic Analysis (doped)Analysis (doped)
DefectsDefects
5% N5% N2 2 dopeddoped
20% N20% N2 2 dopeddoped
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Size Effect Size Effect –– Applicability of Applicability of Weibull Weibull TheoryTheoryundopedundoped
20% N20% N2 2 dopeddoped10% N10% N2 2 dopeddoped
5% N5% N2 2 dopeddoped
m = 11.6, σ0V = 8581 MPa×µm3/m
m = 9.3, σ0V = 5719 MPa×µm3/mm = 9.7, σ0V = 5786 MPa×µm3/m
m = 10.7, σ0V = 5933 MPa×µm3/m
Micro and Nanomechanics LabDepartment of Mechanical Engineering
WeibullWeibull Studies of Studies of SiCSiC (CWRU) and (CWRU) and tata--C (SNL)C (SNL)
S iC
0
0 .10 .2
0 .3
0 .40 .5
0 .6
0 .7
0 .80 .9
1
6 0 0 16 0 0 2 6 0 0 3 6 0 0F a ilure S t re s s ( M P a)
Size A
Size B
t a - C
00.10.20.30.40.50.60.70.80.9
1
3000 4000 5000 6000 7000F a ilure S tre s s (M P a )
Size ASize B
Size A: 20µm wide, 200µm long, and 1 µm thick
Size B: 5mm wide, 100mm long, and 0.5 mm thick
SiC is deposited in a hot-wall, rf-induction-heated, (LPCVD) furnace. ta-C (hydrogen-free tetrahedral amorphous carbon) is deposited by pulsed laser deposition (PLD).
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Determining the Scaling ParametersDetermining the Scaling ParametersSiC
6
8
10
12
14
0.5 1.5 2.5 3.5
Cha
ract
eris
tic S
treng
ths
(*)
Size ASize BPooled value
Volume Surface Sidewall
DLC
7
8
9
10
11
12
0.5 1.5 2.5 3.5
Cha
ract
eris
tic S
treng
ths
(*) Size ASize BPooled value
Volume Surface Sidewall
Mirror region
Ta-C
Mirror region
Si-C
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Fracture Strength Fracture Strength –– WeibullWeibull VerificationVerification
SiC
-5
-4
-3
-2
-1
0
1
2
2000 4000 6000 8000 10000Fracture Strength (MPa)
LN(L
N(1
/(1-P
f))
Pooled
DLC
-5
-4
-3
-2
-1
0
1
2
5000 7000 9000Fracture Strength (MPa)
LN(L
N(1
/(1-P
f))
Pooled
ta-C
−−= e
m
Af AP )(exp1
0
max
σσ
m = 5.4
σ0A = 6780 MPaxµm2/m
m = 12
σ0A = 8020 MPaxµm2/m
Sidewalls are the scaling factors for SiC and ta-C
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Summary of the Mechanical PropertiesSummary of the Mechanical Propertiesand and Weibull Weibull ParametersParameters
SidewallVolumeSidewallScaling parameter
8020±401 [(MPa×(µm)2/m]
8560±428 [(MPa×(µm)3/m]
6780±339 [(MPa×(µm)2/m]σ0V or σ0A
12.0±0.6011.6±0.585.4±0.27Weibull modulus
5260±4594680±5405080±5553990 ±4282680 ±5562090 ±519Fracture Strength at 63% prob. (MPa)
795±34801±22955±21960±25435±15422±18Young’s modulus (GPa)
501±12896±33515±211050±77527±29855±53Thickness (nm)
303030303030No. of tests
Size BSize ASize BSize ASize BSize A
ta-CUNCDSiCMaterial
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Thin Film Fracture ToughnessThin Film Fracture Toughnessand Theoretical Strength and Theoretical Strength
EstimateEstimate
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Fracture Toughness Fracture Toughness –– Sharp CrackSharp Crack
)(WafaK fIC πσ=
σ σ
a
W
4.10.7018.18.2
4.50.7118.26.6
4.70.7818.05.8
4.40.9518.23.9
4.11.3518.12.1
KIC
(MPa m1/2)
σfexp
(GPa)
W
(µm)
a
(µm)
H.D. Espinosa and B. Peng, J. MEMS, 2004
...)(72.21)(55.10)(23.012.1)( 32
Wa
Wa
Wa
Waf −+−=
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Stress Intensity Stress Intensity –– Blunt NotchesBlunt Notches
σ σa
a
W
1 2
10 µm
6.9----Average
6.91.534.915
7.01.734.114
6.61.674.013
6.41.683.712
6.91.883.511
6.51.783.510
6.82.082.79
6.62.142.48
6.62.192.37
6.72.282.26
7.02.412.15
6.42.272.04
6.52.461.73
7.12.691.72
6.93.231.01
K’IC(MPa m1/2)
σfexp
(GPa)a
(µm)SampleNumber
)(WafaK fIC πσ=
32 )(44.15)(78.4)(429.012.1)(Wa
Wa
Wa
Waf +−+=
Crack tipFracture surface
1 µm
H.D. Espinosa and B. Peng, Submitted to J. MEMS, 2004
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Blunt Notch CorrectionBlunt Notch Correction
ρnotch
x
y
a
ρ
( )
+=
xxKx I
y 21
2ρ
πσ ICIC K
xK
+=
21/ ρ
( )∫ ≥0
0dd
uy dxx σσ
ICIC Kd
K0
/
21 ρ+= 2
2
02
u
ICKdσπ
=
Novozhilov’s brittle fracture criterion, 1969
Stress field for blunt crack (Creager, 1967) Drory et al. 1995
σu is a strength characteristic value for the material without defects (the ideal strength of the material at the characteristic size of d0 )
N. Pugno, B. Peng, and H.D. Espinosa, Int. J. Sol. Struc., 2004
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Blunt Notch CorrectionBlunt Notch Correction
a
ρ
a
ρ
a
ρ
35.79.22.8516.22.2490
37.07.93.5516.21.2230
33.58.63.5216.31.4220
39.27.82.5016.12.1170
35.67.32.2516.12.2140
37.37.02.0416.22.4100
d0
[nm]
Κ’IC[MPa m1/2]
σf(exp)[GPa]
W
[µm]
a
[µm]
ρ
[nm]
dd00 is estimated to be ~37 nm and is estimated to be ~37 nm and σσuu = 18 = 18 GPaGPa
N. Pugno, B. Peng, and H.D. Espinosa, Int. J. Sol. Struc., 2004
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Quantum Mechanics Quantum Mechanics SimulationsSimulations
G.C. Schatz, T. G.C. Schatz, T. Belytschko Belytschko and Z. Cheng (UMC)and Z. Cheng (UMC)
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Method Used for Determining Modulus and Method Used for Determining Modulus and Fracture PropertiesFracture Properties
MSINDO: A semi-empirical molecular orbital program. Electron repulsion is included explicitly but most integrals are modeled. Two- and three-dimensional periodic boundary conditions are available in this code.
UNCD models: Some include grain boundaries (GBs).
no GB one GB two GBs
Micro and Nanomechanics LabDepartment of Mechanical Engineering
EnergyEnergy--Strain Curve for Strain Curve for UndopedUndoped Diamond with 2Diamond with 2--D D Boundary Condition and One Grain BoundaryBoundary Condition and One Grain Boundary
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Diamond with 2Diamond with 2--D Boundary Conditions, and One D Boundary Conditions, and One Grain Boundary Grain Boundary DopedDoped with Two Nitrogen Atomswith Two Nitrogen Atoms
Micro and Nanomechanics LabDepartment of Mechanical Engineering
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
0
1
2
3
4
Diamond with 2Diamond with 2--D Boundary Conditions, and One D Boundary Conditions, and One Grain Boundary Grain Boundary DopedDoped with Two Nitrogen Atomswith Two Nitrogen Atoms
Applying strain in different ways can result in qualitatively different fracture paths.
Micro and Nanomechanics LabDepartment of Mechanical Engineering
EnergyEnergy--Strain Curve for Strain Curve for UndopedUndoped Diamond with 3Diamond with 3--D D Boundary Conditions and Two Grain BoundariesBoundary Conditions and Two Grain Boundaries
Micro and Nanomechanics LabDepartment of Mechanical Engineering
EnergyEnergy--Strain Curve for Strain Curve for UndopedUndoped Diamond with 3Diamond with 3--D D Boundary Conditions and No Grain BoundariesBoundary Conditions and No Grain Boundaries
Micro and Nanomechanics LabDepartment of Mechanical Engineering
RemarksRemarks
Two- and three-dimensional boundary condition calculations predict UNCD mechanical properties that are the same, semi-quantitatively.
Doping with two two nitrogen atoms is not sufficient to substantially alter the mechanical properties of UNCD.
Issues related to the existence of multiple fracture pathsmultiple fracture paths complicate the analysis.
Unstrained Strain = 0.1 Broken
Micro and Nanomechanics LabDepartment of Mechanical Engineering
AFM Chips with Wear AFM Chips with Wear Resistant TipsResistant Tips
N. N. MoldovanMoldovan, B. , B. PengPeng, H.D. Espinosa and M. , H.D. Espinosa and M. Hersam Hersam
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Contact Mode AFM Contact Mode AFM PotentiometryPotentiometryExperimental Setup:
A
Onset offailure
0.8V 1V
Evolution of nanowire failure:
M. C. Hersam, A. C. F. Hoole, S. J. O'Shea, and M. E. Welland, Appl. Phys. Lett., 72, 915 (1998).
(Breakdown current density = 3.75×1012 A/m2)Wire width = 60 nm
B
Failurepoint
0.9V 1.8V
Conductive tip with small Rc (kΩ range).
Low Rc must be sustained after extensive scanning.
Micro and Nanomechanics LabDepartment of Mechanical Engineering
UNCD UNCD PotentiometryPotentiometry ChipChip
Au h~100-500 µm
UNCDdoped to be conductive
Phase 1 : A single probe chip
Conductive AFM techniques can be improved with tips Conductive AFM techniques can be improved with tips coated with conformal and highly conductive UNCD films.coated with conformal and highly conductive UNCD films.
h~3-7 µm
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Preliminary ResultsPreliminary Results
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Molecular Writing with Diamond Tips
MHA solution in ethanol with concentration at 1 mM• scan rate: 6 Hz• vertical deflection: -2 V (left), -1 (right)• contact time: 50, 25, and 13 sec• gains: (Int, Prop, LookAhead) = (4, 4, 0)• patterning on a Au substrate prepared on 7/2/04 (left), 7/8 (right)• image processing: low pass & detrend (left)
Science 283, 661 (1999)
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Massively Parallel UNCD Massively Parallel UNCD PotentiometryPotentiometryPhase 2 : Integrated multiple probes
Contact pads
UNCD
PYREX 7740
Si (B++ doped)eventually oxidized
•Independent electrodes for potentiometry
•Independent actuation (thermal?)
•Multiplexing
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Thermal Actuation / MultiplexingThermal Actuation / Multiplexing
Crossing-over of lines multiple metallization (2+1)
Insulator layer increase in stiffness
Parasitic capacitances
Address Input Lines
col 1 col 2 col NColum n Select
row 1
row 2
row 3
row M
Data Input Buffers and
Control
Micro and Nanomechanics LabDepartment of Mechanical Engineering
NEMS NEMS NanoresonatorsNanoresonatorsAnomalous Q FactorAnomalous Q FactorBreak down of Break down of WeibullWeibull
B.B. PengPeng, N. , N. MoldovanMoldovan, H.D. Espinosa, H.D. Espinosa
Micro and Nanomechanics LabDepartment of Mechanical Engineering
UNCD UNCD NanoresonatorsNanoresonators-- Anomalous Q FactorAnomalous Q Factor
ραϖ
12
2 EtL
=
StoredEnergy DissipatedEnergy
=QE-beam lithography pattern
Micro and Nanomechanics LabDepartment of Mechanical Engineering
Concluding RemarksConcluding Remarks• Mechanical properties of UNCD were investigated by this
work. Young’s modulus of 960 GPa, fracture strength of 5 GPa for undoped UNCD, fracture toughness of 4.5 MPam1/2, and ideal strength of 18.6 GPa associated to a characteristic length of 37 nm.
• We showed that Weibull statistics is capable of predicting fracture strengths of MEMS materials with different sizes.
• Molecular dynamics model was used to simulate the mechanical properties from atomic species and imperfections.
• AFM cantilevers with sharp tips made of UNCD have been microfabricated and molecular writing demonstrated.
Micro and Nanomechanics LabDepartment of Mechanical Engineering
http://clifton.mech.northwestern.edu/~espinosa/
B. Peng, Northwestern UniversityN. Moldovan, Northwestern UniversityO. Auciello, ANLJ. Carlisle, ANLX. Xiao, ANLM. Hersam, Northwestern UniversityG.C. Schatz, Northwestern UniversityT. Belytschko, Northwestern UniversityB. Prorok, Aurburn University
Acknowledgments:Acknowledgments:
NSF-Nano Science Interdisciplinary Research Teams (NIRT), Award Number CMS-00304472 National Science Foundation, GOALI Award No. CMS-0120866/001
Ivan Petrov, UIUCD. Mancini, ANLJ. Mahon, UIUCM. Marshall, UIUCR.S. Divan, ANLZ. Chen, UMCC.A. Zorman, CWRUT.A. Friedmann, SNLN. Pugno, Politecnico di Torino, Italy
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