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Micro and Nanomechanics Lab Department of Mechanical Engineering

Science and Technology of Science and Technology of Ultrananocrystalline Ultrananocrystalline Diamond Films for Multifunctional MEMS/NEMS Diamond 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 Lab Department of Mechanical Engineering

Outline Outline

NIRT Project Overview Film Deposition and Characterization Identification of Mechanical Properties Multiscale Modeling starting from Quantum Mechanics Applications: AFM Potentiometry Molecular Writing and Self Assembly NEMS, e.g., nanoresonators

Micro and Nanomechanics Lab Department of Mechanical Engineering

Participating Institutions/Overview Participating Institutions/Overview

Micro and Nanomechanics Lab Department of Mechanical Engineering

Ultrananocrystalline Ultrananocrystalline Diamond Films For Diamond Films For Multifunctional MEMS/NEMS Devices Multifunctional 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
• …

ρ α ϖ 12

2

E t L =

Micro and Nanomechanics Lab Department of Mechanical Engineering

Film Deposition Film Deposition

Orlando Orlando Auciello Auciello and John Carlisle (ANL) and John Carlisle (ANL)

Micro and Nanomechanics Lab Department of Mechanical Engineering

iPlas iPlas Microwave Plasma CVD System at ANL Microwave Plasma CVD System at ANL

OES of Ar/CH4 Plasma

200 400 600 800 1000 1200

C2- Main species for the growth of UNCD

C2 emission

Intensity (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 W UNCD 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 Lab Department of Mechanical Engineering

Grain Size vs. Grain Size vs. Ar Ar Ratio Ratio

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 broadened diamond band is broadened

Micro and Nanomechanics Lab Department of Mechanical Engineering

Grain Size vs. N Grain Size vs. N2

2 Ratio

Ratio

(a) 0% N (a) 0% N2

2 UNCD, (b) 5% N

UNCD, (b) 5% N2

2 UNCD, (c) 10% N

UNCD, (c) 10% N2

2 UNCD, (d) 20% N

UNCD, (d) 20% N2

2

• UNCD. 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. N increases from 0.5 to 2.2 nm. N2

2 is incorporated preferentially at the

is incorporated preferentially at the grain boundaries. grain boundaries.

Grain + Grain boundary morphology Grain + Grain boundary morphology

J.

• J. Birrell

Birrell et al., App. Phys. Let., Vol. 81, pp. 2235 et al., App. Phys. Let., Vol. 81, pp. 2235-

• 2237, 2002.

2237, 2002.

Micro and Nanomechanics Lab Department of Mechanical Engineering

100 nm

Super Grains Super Grains

Micro and Nanomechanics Lab Department of Mechanical Engineering

Scanning Probe Microscopy Characterization of Scanning Probe Microscopy Characterization of UNCD UNCD

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 Lab Department of Mechanical Engineering

Scanning Probe Microscopy Characterization of Scanning Probe Microscopy Characterization of UNCD ( UNCD (con’t con’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 Lab Department of Mechanical Engineering

Contact Mode AFM Measurements Contact Mode AFM Measurements

Initial cAFM Data (Undoped vs. N2 Doped UNCD)

2E-11 4E-11 6E-11 8E-11 1E-10 1.2E-10 2 4 6 8 10 12 Voltage (V) Current (A) Upsweep Downsweep 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 2 4 6 8 10 12 Voltage (V) Current (A) Upsweep Downsweep

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 Lab Department of Mechanical Engineering

Mechanical Testing Mechanical Testing

• Modulus

Modulus

• Strength

Strength

• Fracture Toughness

Fracture Toughness

Micro and Nanomechanics Lab Department of Mechanical Engineering

Wafer Level Micro Wafer Level Micro-

• scale Tension Test

scale 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 Area Line-load Tip Membrane Interferometric Objective

Micro and Nanomechanics Lab Department of Mechanical Engineering

UNCD MDE Specimens UNCD MDE Specimens

20 µm

Non-uniformities due to wafer seeding process

200 µm

4” wafer

Micro and Nanomechanics Lab Department of Mechanical Engineering

Fabrication Steps Fabrication 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 Lab Department of Mechanical Engineering

Stress Calculations Stress Calculations

PV Wafer Mirau Microscope Objective PM PM θ LM ∆

) sin( 2 ) ( ) ( θ σ

m V

A t P t =

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 Lab Department of Mechanical Engineering

Strain Calculations Strain Calculations

λ = wavelength of interferometer light. δ = distance between fringes

ε(t) = Strain at time t

Strain

1 ) 2 / ( ) (

2 2

− + = δ λ δ ε t

θ1 Fringes (c) 3λ/4 λ/2 λ/4 λ/2 δ Fringes Bottom surface of membrane

Micro and Nanomechanics Lab Department of Mechanical Engineering

Stess Stess-

• Strain Curves

Strain Curves

500 1000 1500 2000 2500 3000 3500 4000 4500 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

σ σf1

f1 = 4.17

= 4.17 GPa GPa σ σf2

f2 = 2.71

= 2.71 GPa GPa σ σf3

f3 = 2.45

= 2.45 GPa GPa σ σf4

f4 = 2.35

= 2.35 GPa GPa

The stress at 63% failure probability

2350 2350 2446 2446 2713 2713 4172 4172 σ σ0

0 (

(MPa MPa) ) 833 833-

• 865

865 854 854-

• 880

880 878 878-

• 921

921 940 940-

• 970

970 E ( E (GPa GPa) ) 30 30 30 30 30 30 30 30

• No. of tests
• No. of tests

20% 20% 10% 10% 5% 5% 0% 0% N N2

2 percentage

percentage Doped Doped Undoped Undoped Sample Sample

Micro and Nanomechanics Lab Department of Mechanical Engineering

200 200 400 800 Side Wall Area (µm2) 1200 8200 8400 32800 Total Surface Area (µm2) 500 2000 4000 16000 Volume (µm3) 1 0.5 1 1 Thickness (µm) 5 20 20 40 Width (µm) 100 200 200 400 Length (µm)

D C B A Samples

undoped undoped

• B. Peng et al., submitted to
• J. Appl. Phys., 2004

                − − =

m Weibull f

V V P

max

exp 1 σ σ

N i Pf 2 / 1

exp

− =

                − − =

m Weibull f

A A P

max

exp 1 σ σ

Size Effect Size Effect – – Applicability of Applicability of Weibull Weibull Theory Theory

Micro and Nanomechanics Lab Department of Mechanical Engineering

Weibull Weibull Two Two-

• parameter Model

parameter Model

• r

     − − =

e m V f

V P ) ( exp 1

max

σ σ      − − =

e m A f

A P ) ( exp 1

max

σ σ

6.5 7.5 8.5 9.5 10.5 11.5 0.5 1.5 2.5 3.5 Scaling Parameters Characteristic Strengths (σ0V orσ0V) Size A Size B Size C Size D

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) Probability of Failure

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 Lab Department of Mechanical Engineering

Fractographic Fractographic Analysis ( Analysis (undoped undoped) )

2 µm

Grain nucleation layer Top surface

Cluster of grains

Intergrannular Fracture

Polysilicon

W.N. Sharpe et al., J. MEMS, Vol. 12, 2003

Micro and Nanomechanics Lab Department of Mechanical Engineering

Fractographic Fractographic Analysis (doped) Analysis (doped)

Defects Defects 5% N 5% N2

2 doped

doped 20% N 20% N2

2 doped

doped

Micro and Nanomechanics Lab Department of Mechanical Engineering

Size Effect Size Effect – – Applicability of Applicability of Weibull Weibull Theory Theory

undoped undoped 20% N 20% N2

2 doped

doped 10% N 10% N2

2 doped

doped 5% N 5% N2

2 doped

doped

m = 11.6, σ0V = 8581 MPa×µm3/m m = 9.3, σ0V = 5719 MPa×µm3/m m = 9.7, σ0V = 5786 MPa×µm3/m m = 10.7, σ0V = 5933 MPa×µm3/m

Micro and Nanomechanics Lab Department of Mechanical Engineering

Weibull Weibull Studies of Studies of SiC SiC (CWRU) and (CWRU) and ta ta-

• C (SNL)

C (SNL)

S iC 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 600 1600 2600 3600 Failure S t re s s ( M Pa) Size A Size B t a- C

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 3000 4000 5000 6000 7000 F a ilure S tre s s (M P a )

Size A Size 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 Lab Department of Mechanical Engineering

Determining the Scaling Parameters Determining the Scaling Parameters

SiC

6 8 10 12 14

0.5 1.5 2.5 3.5

Characteristic Strengths (*)

Size A Size B Pooled value

Volume Surface Sidewall DLC

7 8 9 10 11 12

0.5 1.5 2.5 3.5

Characteristic Strengths (*)

Size A Size B Pooled value

Volume Surface Sidewall Mirror region

Ta-C

Mirror region

Si-C

Micro and Nanomechanics Lab Department of Mechanical Engineering

Fracture Strength Fracture Strength – – Weibull Weibull Verification Verification

SiC

• 5
• 4
• 3
• 2
• 1

1 2 2000 4000 6000 8000 10000 Fracture Strength (MPa) LN(LN(1/(1-Pf))

Pooled

DLC

• 5
• 4
• 3
• 2
• 1

1 2 5000 7000 9000 Fracture Strength (MPa) LN(LN(1/(1-Pf))

Pooled

ta-C

     − − =

e m A f

A P ) ( exp 1

max

σ σ

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 Lab Department of Mechanical Engineering

Summary of the Mechanical Properties Summary of the Mechanical Properties and and Weibull Weibull Parameters Parameters

Sidewall Volume Sidewall Scaling parameter 8020±401 [(MPa×(µm)2/m] 8560±428 [(MPa×(µm)3/m] 6780±339 [(MPa×(µm)2/m] σ0V or σ0A 12.0±0.60 11.6±0.58 5.4±0.27 Weibull modulus 5260±459 4680±540 5080±555 3990 ±428 2680 ±556 2090 ±519 Fracture Strength at 63% prob. (MPa) 795±34 801±22 955±21 960±25 435±15 422±18 Young’s modulus (GPa) 501±12 896±33 515±21 1050±77 527±29 855±53 Thickness (nm) 30 30 30 30 30 30

• No. of tests

Size B Size A Size B Size A Size B Size A ta-C UNCD SiC Material

Micro and Nanomechanics Lab Department of Mechanical Engineering

Thin Film Fracture Toughness Thin Film Fracture Toughness and Theoretical Strength and Theoretical Strength Estimate Estimate

Micro and Nanomechanics Lab Department of Mechanical Engineering

Fracture Toughness Fracture Toughness – – Sharp Crack Sharp Crack

) (W a f a K

f IC

π σ =

σ σ

a

W

4.1 0.70 18.1 8.2 4.5 0.71 18.2 6.6 4.7 0.78 18.0 5.8 4.4 0.95 18.2 3.9 4.1 1.35 18.1 2.1 KIC (MPa m1/2) σf

exp

(GPa) W (µm) a (µm) H.D. Espinosa and B. Peng, J. MEMS, 2004

... ) ( 72 . 21 ) ( 55 . 10 ) ( 23 . 12 . 1 ) (

3 2

W a W a W a W a f − + − =

Micro and Nanomechanics Lab Department of Mechanical Engineering

Stress Intensity Stress Intensity – – Blunt Notches Blunt Notches σ σ

a a

W

1 2

10 µm

6.9

• Average

6.9 1.53 4.9 15 7.0 1.73 4.1 14 6.6 1.67 4.0 13 6.4 1.68 3.7 12 6.9 1.88 3.5 11 6.5 1.78 3.5 10 6.8 2.08 2.7 9 6.6 2.14 2.4 8 6.6 2.19 2.3 7 6.7 2.28 2.2 6 7.0 2.41 2.1 5 6.4 2.27 2.0 4 6.5 2.46 1.7 3 7.1 2.69 1.7 2 6.9 3.23 1.0 1 K’IC (MPa m1/2) σf

exp

(GPa) a (µm) Sample Number

) (W a f a K

f IC

π σ =

3 2

) ( 44 . 15 ) ( 78 . 4 ) ( 429 . 12 . 1 ) ( W a W a W a W a f + − + =

Crack tip Fracture surface

1 µm

H.D. Espinosa and B. Peng, Submitted to J. MEMS, 2004

Micro and Nanomechanics Lab Department of Mechanical Engineering

Blunt Notch Correction Blunt Notch Correction

ρ notch x y

a

ρ

( )

      + = x x K x

I y

2 1 2 ρ π σ

IC IC

K x K       + = 2 1

/

ρ

( )

∫

≥ d

d u y

d x x σ σ

IC IC

K d K

/

2 1 ρ + =

2 2

2

u IC

K d σ π =

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 Lab Department of Mechanical Engineering

Blunt Notch Correction Blunt Notch Correction

a

ρ

a

ρ

a

ρ

35.7 9.2 2.85 16.2 2.2 490 37.0 7.9 3.55 16.2 1.2 230 33.5 8.6 3.52 16.3 1.4 220 39.2 7.8 2.50 16.1 2.1 170 35.6 7.3 2.25 16.1 2.2 140 37.3 7.0 2.04 16.2 2.4 100

d0 [nm] Κ’IC [MPa m1/2] σf

(exp)

[GPa] W [µm] a [µm] ρ [nm]

d d0

0 is estimated to be ~37 nm and

is estimated to be ~37 nm and σ σu

u = 18

= 18 GPa GPa

• N. Pugno, B. Peng, and H.D. Espinosa, Int. J. Sol. Struc., 2004

Micro and Nanomechanics Lab Department of Mechanical Engineering

Quantum Mechanics Quantum Mechanics Simulations Simulations

G.C. Schatz, T. G.C. Schatz, T. Belytschko Belytschko and Z. Cheng (UMC) and Z. Cheng (UMC)

Micro and Nanomechanics Lab Department of Mechanical Engineering

Method Used for Determining Modulus and Method Used for Determining Modulus and Fracture Properties Fracture 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

• ne GB

two GBs

Micro and Nanomechanics Lab Department of Mechanical Engineering

Energy Energy-

• Strain Curve for

Strain Curve for Undoped Undoped Diamond with 2 Diamond with 2-

• D

D Boundary Condition and One Grain Boundary Boundary Condition and One Grain Boundary

Micro and Nanomechanics Lab Department of Mechanical Engineering

Diamond with 2 Diamond with 2-

• D Boundary Conditions, and One

D Boundary Conditions, and One Grain Boundary Grain Boundary Doped Doped with Two Nitrogen Atoms with Two Nitrogen Atoms

Micro and Nanomechanics Lab Department 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 1 2 3 4

Diamond with 2 Diamond with 2-

• D Boundary Conditions, and One

D Boundary Conditions, and One Grain Boundary Grain Boundary Doped Doped with Two Nitrogen Atoms with Two Nitrogen Atoms

Applying strain in different ways can result in qualitatively different fracture paths.

Micro and Nanomechanics Lab Department of Mechanical Engineering

Energy Energy-

• Strain Curve for

Strain Curve for Undoped Undoped Diamond with 3 Diamond with 3-

• D

D Boundary Conditions and Two Grain Boundaries Boundary Conditions and Two Grain Boundaries

Micro and Nanomechanics Lab Department of Mechanical Engineering

Energy Energy-

• Strain Curve for

Strain Curve for Undoped Undoped Diamond with 3 Diamond with 3-

• D

D Boundary Conditions and No Grain Boundaries Boundary Conditions and No Grain Boundaries

Micro and Nanomechanics Lab Department of Mechanical Engineering

Remarks Remarks

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 paths multiple fracture paths complicate the analysis.

Unstrained Strain = 0.1 Broken

Micro and Nanomechanics Lab Department of Mechanical Engineering

AFM Chips with Wear AFM Chips with Wear Resistant Tips Resistant Tips

N.

• N. Moldovan

Moldovan, B. , B. Peng Peng, H.D. Espinosa and M. , H.D. Espinosa and M. Hersam Hersam

Micro and Nanomechanics Lab Department of Mechanical Engineering

Contact Mode AFM Contact Mode AFM Potentiometry Potentiometry

Experimental Setup:

A

Onset of failure 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

Failure point 0.9V 1.8V

Conductive tip with small

Rc (kΩ range).

Low Rc must be

sustained after extensive scanning.

Micro and Nanomechanics Lab Department of Mechanical Engineering

UNCD UNCD Potentiometry Potentiometry Chip Chip

Au h~100-500 µm UNCD

doped 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 Lab Department of Mechanical Engineering

Preliminary Results Preliminary Results

Micro and Nanomechanics Lab Department 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 Lab Department of Mechanical Engineering

Massively Parallel UNCD Massively Parallel UNCD Potentiometry Potentiometry

Phase 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 Lab Department of Mechanical Engineering

Thermal Actuation / Multiplexing Thermal 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 N Colum n Select row 1 row 2 row 3 row M Data Input Buffers and Control

Micro and Nanomechanics Lab Department of Mechanical Engineering

NEMS NEMS Nanoresonators Nanoresonators

Anomalous Q Factor Anomalous Q Factor Break down of Break down of Weibull Weibull

B.

• B. Peng

Peng, N. , N. Moldovan Moldovan, H.D. Espinosa , H.D. Espinosa

Micro and Nanomechanics Lab Department of Mechanical Engineering

UNCD UNCD Nanoresonators Nanoresonators-

• Anomalous Q Factor

Anomalous Q Factor

ρ α ϖ 12

2

E t L = Stored Energy Dissipated Energy = Q

E-beam lithography pattern

Micro and Nanomechanics Lab Department of Mechanical Engineering

Concluding Remarks Concluding 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 MPa m1/2, 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 Lab Department of Mechanical Engineering

http://clifton.mech.northwestern.edu/~espinosa/

• B. Peng, Northwestern University
• N. Moldovan, Northwestern University
• O. Auciello, ANL
• J. Carlisle, ANL
• X. Xiao, ANL
• M. Hersam, Northwestern University

G.C. Schatz, Northwestern University

• T. Belytschko, Northwestern University
• B. 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, UIUC

• D. Mancini, ANL
• J. Mahon, UIUC
• M. Marshall, UIUC

R.S. Divan, ANL

• Z. Chen, UMC

C.A. Zorman, CWRU T.A. Friedmann, SNL

• N. Pugno, Politecnico di Torino,

Italy