Large-Area Synthesis of High-Quality and Controllable Thickness - - PowerPoint PPT Presentation

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Large-Area Synthesis of High-Quality and Controllable Thickness - - PowerPoint PPT Presentation

Nov 26, 2023 380 likes •549 views

THE 10 th KOREA-U.S NANOFORUM A New Generation of Nanotechnological Product and Process Large-Area Synthesis of High-Quality and Controllable Thickness Graphene Films by Rapid Thermal Annealing Ph.D Candidate : Jae Hwan Chu School of

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THE 10th KOREA-U.S NANOFORUM

Large-Area Synthesis of High-Quality and Controllable Thickness Graphene Films by Rapid Thermal Annealing

Ph.D Candidate

: Jae Hwan Chu

School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology

A New Generation of Nanotechnological Product and Process

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THE 10th KOREA-U.S NANOFORUM

Rapid Thermal Annealing (RTA)

  • Nickel – assisted graphene grow th using RTA
  • Spontaneous formation , Carbon- and oxygen-containing compounds
  • Few-layer graphene films were formed on a nickel surface
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THE 10th KOREA-U.S NANOFORUM

Rapid Thermal Annealing (RTA)

  • Temperature (800 ~1000℃) & Various ambient
  • Few -layer graphene film s are form ed under vacuum ( ∼1 0 -3 Torr)

at tem p. ranging from 8 0 0 and 1 0 0 0 for 0 .5 – 4 m in

  • No graphene form w hen inert gases are introduced during the RTA process
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THE 10th KOREA-U.S NANOFORUM

Growth mechanism

  • Presence of Ar or N 2 during RTA m ay lead to a m uch reduced oxygen evaporation rate

→ The oxygen atoms desorbing from the surface have a finite probability of being

reflected back to the nickel surface by collision with Ar or N2, as pointed out by Langmuir and Fonda. (Phys. Rev. 43, 401 (1912), (Phys. Rev. 31 (260))

1) Inert gas - RTA No significant change in oxygen concentration → No graphene form 2) Vacuum – RTA Graphene forms in all investigated temperature, along with oxygen evaporation from surface

  • Dominant factor – oxygen evaporation rate
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THE 10th KOREA-U.S NANOFORUM

The thickness and physical properties of the graphene layers are strongly dependent on the RTA temperature and time.

Characterization

  • f graphene at RTA-vacuum
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THE 10th KOREA-U.S NANOFORUM

Conclusion

  • The m erits of our m ethod are as follow s.

1) Simply grown by annealing the nickel films at high temperature under vacuum 2) The consuming time of process is highly short 3) The thickness of graphene layers is controlled by RTA temperature and time 4) comparable structural and optoelectronic qualities with CVD- graphene

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THANK YOU

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Any other questions?

ACS Appled Materials & Interface 4(3): 1777 (2012)

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THE 10th KOREA-U.S NANOFORUM

Supporting information

Supporting Information

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THE 10th KOREA-U.S NANOFORUM

Experiments (RTA method)

  • The nickel films
  • Deposited in com m ercial evaporators ( ~ 1 0 -6-1 0 -7 Torr) w ith solid Ni( 9 9 .9 9 % )
  • Thickness of ~ 1 0 0 nm deposited on a SiO2 ( 3 0 0 nm ) / Si( 1 0 0 ) substrate
  • The source and stored under atm osphere for a typical period of a few days.
  • RTA(Rapid Thermal Annealing)
  • Tem peratures ranging from 8 0 0 oC to 1 ,0 0 0 oC for 0 .5 - 4 m in
  • Vacuum ( ~ 1 0 -3 Torr)
  • I n inert gas ( Ar, N 2) am bient ( ~ 0 .2 -2 .0 Torr)
  • How to employ the source of carbon
  • Trace am ounts of unintentionally introduced carbon and oxygen atom s after

Ni deposition

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THE 10th KOREA-U.S NANOFORUM

How to make graphene?

Table 1. Comparison of different methods for graphene production

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THE 10th KOREA-U.S NANOFORUM

Rapid Thermal Annealing (RTA)

  • An attractive method
  • large area graphene synthesis >

6inch

  • good optical, electrical and

mechanical properties

  • applying various applications

CVD

method

Why should the CVD method be improved?

1) Required various parameters 2) Difficult control for growth. 3) Total process time is long. 4) Price.

  • K. Novoselov, Nature 4 9 0 , 1 9 2 ( 2 0 1 2 ) .

Rapid Thermal Annealing

  • RTA method
  • Facile synthesis of large-area

graphene

  • A simple and reproducible method
  • without intentional carbon- containing

precursor

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THE 10th KOREA-U.S NANOFORUM

How to employ the source of carbon

  • XPS concentration-depth profile of Ni films before RTA process
  • The presence of Ultrathin

Compounds on a Nickel Surface

C 1s Ni3C 283.9 eV NiCO3 288.4 eV O 1s NiO 529.7 eV NiCO3 531.3 eV Ni 2p Ni3C 852.9 eV NiO 853.8 eV NiCO3 854.7 eV Trace am ounts of unintentionally introduced carbon and

  • xygen atom s after Ni deposition
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  • 1) As deposition, 2) RTA in N2 at 900℃ 1min , 3) RTA in vacuum at 900℃ 1min

What makes difference growth condition?

  • XPS concentration profile
  • considerable com positional changes only vacuum am bient
  • m ost oxygen atom s disappear after the vacuum – RTA process
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THE 10th KOREA-U.S NANOFORUM

What makes difference growth condition?

  • XPS Depth profile
  • 1) As deposition, 2) RTA in N2 at 900℃ 1min , 3) RTA in vacuum at 900℃ 1min

Table 4. the composition(%) of the top surface according to C1s and O1s Carbon composition(%) Oxygen composition(%) As-grown 27.73% 35.68% RTA in N2 25.26% 30.94% RTA in vacuum 85.92% 2.36% Ambient elements