Micromechanical Nanographite Resonators Older

8/17/2019 Micromechanical Nanographite Resonators Older

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Characterisation ofnanographite for MEMS

resonators

Sam Fishlock, Harold Chong, John McBride,

Sean O’Shea, Suan Hui PuMS Fall meeting practice session

s!f"e"#$soton%ac%uk



Car&on materials for MEMS and'EMS

•

MEMS ( Micro Electro)Mechanical S*stems• +nestigated materials- diamond)like car&on, graphite,

graphene

• .pplications- resonators as mass sensors or oscillators and/lters for electronics

• 0ood mechanical properties and deice scala&ilit*• .+M- 1emonstrate fa&rication and characterisation of

nanographite MEMS resonators 2ithout transfer

F% ose et% al, 'anotechnolog*% "34 5#6678 4"9#%:%M% Milaninia et% al, .ppl% Ph*s% ;ett% 94 5#6698



'anocr*stalline graphitedeposition

• 7)inch silicon 2afer su&strate

• O=ford instruments '.'OF.BPEC>1

• Scala&le and reproduci&le ?

standard microfabricationprocess

@emperature 5AC8 46

Methane o25sccm8

4

H*drogen o25sccm8

76

Pressure 5m@orr8 "466

F Po2er 5D8 "66

M%E% Schmidt et% .l, Mater% es% E=p% " 5#6"8%222%aom%com



Material characterisation•

aman and SEM con/rm nanocr*stalline grain structure• Electrical resistiit* "6%6 mG cm

• measurement I densit* ρ "966 kgm3

esistiit*&* electricalmeasureme

nts

"66nm



Film stress

Stress gradientin the /lmK

K causescurature incantileers

.pplied

stress

.erage compressie stresscauses &uckling in C)C &eams

#6 um#6 um





Simulation

• Modelled as classic &eams under tension 2here 'aturalfreNuenc* f aries 2ith - ;ength L , Stiness E, densit* ρ,Stress S and 0eometr* factor I,:

• .'SLS FE. simulation sho2s added

length due to the undercut 3Q

'ominallength

Eectie

length

2 2

2 21

EI SL f

L EI

π

ρ π

µ +



;aser source

Split &eam I

1oppler shift usedto calculatei&rationamplitude

.ctuation and measurement• 1C V DC .C V 0 oltage creating electrostatic force F to

actuate the &eam

• S2eep .C oltage at freNuenc* f and measure the i&rationusing ;1> ( )( )2

0

1 12 sin 2

2 2 DC DC

C C F V V V ft

r r π

∂ ∂= ≈ +

∂ ∂

Measured "st i&ration mode



esonance results

• >eri/cation from the FE. model

• Loung’s modulus from the cantileers is #3 0Pa

• FreNuenc* of the dou&l* clamped &eams dominated &*stress

Simulation for Loung’s modulus? #3 0Pa

Cantileerresults 1ou&l* clamped &eam results

9 MPa tensilestress



esults ) Nualit* factor

36 m@orrT ("366

.m&ientT ( #6

• Tualit* factor UT’ I energ* loss at resonance% Calculatedfrom the FDHM of /tted cure

• ;osses are intrinsic, clamping, e=trinsic



+ncreasing &iasoltage

@uning the naturalfreNuenc*

• +ncreasing the 1C &ias applies a compressie stressUelectrostatic spring softening’ to change the naturalfreNuenc*

• 6%34Q per olt aerage tuna&ilit*

•

'on)linearit* due to anchor shape



Conclusions

• oute to standard fa&rication of thin nanographite andnanographene deices &* PEC>1

• Electrostaticall* actuated and tuned resonator deice

• ;o2 modulus, high stress material ? used the stress gradient

to create tensile deices 2hich raises the i&ration freNuenc*



• Dr Suan Hui Pu

• Dr Harold Chong

• Prof John McBride

• 1r :ian :iang

• 1r O2ain Clark

• Mr Michael Perr*

• Dr Sean O’Shea

•

1r iaosong @ang• Mr .ndre2 Breeson

• 1r Me*samMirshekarloo

• Mr ;im Poh Chong

Sincere thanks to co-authors and technicalhelp



Than !ou - "n!#uestions$

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Micromechanical Nanographite Resonators Older