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분자동역학 모사를 통한 비정질 탄소 필름의 원자구조 해석 : RDF 를 중심으로

분자동역학 모사를 통한 비정질 탄소 필름의 원자구조 해석 : RDF 를 중심으로. 이 승 협 , 이 승 철 , 이 광 렬 KIST 미래기술연구본부. KIST Beamline User Workshop (2005. 11. 10). Hard disk. Heart valve. Diamond-like Carbon. Amorphous Solid Carbon Film Mixture of sp 1 , sp 2 and sp 3 Hybridized Bonds High Content of Hydrogen (20-60%)

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분자동역학 모사를 통한 비정질 탄소 필름의 원자구조 해석 : RDF 를 중심으로

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  1. 분자동역학 모사를 통한 비정질 탄소 필름의 원자구조 해석 : RDF를 중심으로 이 승 협, 이 승 철, 이 광 렬 KIST 미래기술연구본부 KIST Beamline User Workshop (2005. 11. 10)

  2. Hard disk Heart valve Diamond-like Carbon • Amorphous Solid Carbon Film • Mixture of sp1, sp2 and sp3 Hybridized Bonds • High Content of Hydrogen (20-60%) • Synonyms • (Hydrogenated) amorphous carbon (a-C:H) • i-Carbon • Tetrahedral Amorphous Carbon (ta-C)

  3. 2-D Analogy of Structure ta-C

  4. High Residual Compressive Stress Film Deposition

  5. Stress Reduction by Si Incorporation C.-S. Lee et al, Diam. Rel. Mater., 11 (2002) 198-203 S.-H. Lee et al, to be Submitted (2005)

  6. Hybrid Force Field Brenner force field for C-C bonds Tersoff force field for C-Si and Si-Si bonds Diamond substrate : 6a0 x 4.75a0 x 6a0 1,368 atoms with 72 atoms per layer Deposition Total 2,000 atoms Incident Kinetic Energy : 75 eV for both C and Si Si concentration : 0.5 % ~ 20 % Molecular Dynamics Simulation Deposited atoms created on this plane Fully Relaxed Layer Fixed Layer

  7. Snapshots after Deposition 0.0 % 3.0 % 0.5 % 5.0 % 1.0 % 10.0 % 2.0 % 20.0 %

  8. Atomic Stress Analysis 300 K Atomic Level Stress Tensor

  9. Residual Compressive Stress Experiment : C.-S. Lee et al, Diam. Rel. Mater., 11, 198 (2002).

  10. Atomic Bond Structure Raman G-peak Position MD Simulation Experiment : C.-S. Lee et al, Diam. Rel. Mater., 11 (2002) 198-203

  11. 2.54 Å 1.54 Å Crystalline Diamond Radial Distribution Function

  12. 2.184 A 2.185 A Radial Distribution Function

  13. 2.184 A 2.185 A Radial Distribution Function

  14. Radial Distribution Function

  15. Bond Angle Distribution

  16. Conclusions • Various properties of a-C films generated by MD simulation agrees well with those of experimentally obtained a-C films. • Brenner force field for C-C bond • Tersoff force field for Si-Si and Si-C bond • Stress reduction mechanism was suggested based on the atomic scale structure analysis. • Small amount of Si incorporation in a-C network effectively relaxes the distorted bonds. • Direct comparison with experimental data will be possible if we obtain the radial distribution function of a-C films.

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