1 / 23

### Atomic Structure Analysis of Diamond-like Carbon Films ####

Explore the bond structure of Carbon 1S2.2S22P2 and the significance of DLC in amorphous solid carbon films. Discover insights into the structure, mechanical properties, and stress reduction mechanisms of these films through molecular dynamics simulations and experimental observations. Learn about the influence of Si incorporation and the role of W atoms in the atomic bond network. ####

pearlieb
Download Presentation

### Atomic Structure Analysis of Diamond-like Carbon Films ####

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Atomic Structure Analysis of Diamond-like Carbon Films S.-H. Lee, S.-C. Lee, H.-S. Ahn, K.-R. Lee Korea Institute of Science and Technology 윤덕용 교수님 정년퇴임 및 최고과학기술자상 수상 기념 심포지움 (한국세라믹스학회, 서울시립대, 2005. 4. 22)

  2. Bond Structure of Carbon 1S2 2S22P2

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

  4. 2-D Analogy of Structure ta-C a-C:H

  5. High Residual Compressive Stress Film Deposition

  6. 2-D Analogy of the Structure Structure and Mechanical Properties • Hardness • 3-D interlink of the atomic bond network • Residual Stress • Distortion of bond angle and length • Both are dependent on the degree of 3-D interlinks.

  7. Hardness Hardness and Residual Stress

  8. Hardness Hardness and Residual Stress

  9. Stress Reduction by Si Incorporation C.-S. Lee et al, Diam. Rel. Mater., 11 (2002) 198-203

  10. 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

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

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

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

  14. Radial Distribution Function

  15. : Silicon atom : Carbon atom : Atoms in calculation Effect of Si Incorporation

  16. Bond Angle Distribution 93.1 Pure ta-C ta-C:Si

  17. W-DLC by Hybrid Ion Beam Deposition Wn+ H+, Cm+  Sputter gun: Third elements addition to DLC (W, Ti, Si …); Ion gun: Easy controlling the ion bombardment energy with high ion flux. A.-Y. Wang et al, Appl. Phys. Lett., 86, 111902 (2005).

  18. Stress & Mechanical Properties 170±15 GPa 21±3 GPa

  19. -W2C (101) 3.6 1.9 4 nm 4 nm 4 nm -W2C(101) 2.8 8.6 -W2C(102) 4 nm TEM Microstructures Nano-crystalline -W2C phases evolve. W atoms are dissolved in a-C:H matrix. Amorphous to crystalline WC1-x transition occurs. -W2C

  20. Ip/Is = 0.550.1 Raman & EELS Spectra

  21. -W2C (101) 3.6 1.9 4 nm 4 nm 4 nm -W2C(101) 2.8 8.6 -W2C(102) 4 nm TEM Microstructures Nano-crystalline -W2C phases evolve. W atoms are dissolved in a-C:H matrix. Amorphous to crystalline WC1-x transition occurs. -W2C

  22. H H C C W C Role of W atoms- ab initio calculation

  23. 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 based on the atomic scale structure analysis • Small amount of Si incorporation in a-C network prohibits carbon atoms from locating at a metastable site. • W atoms dissolved in a-C matrix play a role of pivot site where the atomic bond distortion can occur without inducing a significant increase in elastic energy.

More Related