Thick stress-free amorphous-tetrahedral carbon films with hardness near that of diamond
- Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
- Sandia National Laboratories, Livermore, California 94551 (United States)
We have developed a process for making thick, stress-free, amorphous-tetrahedrally bonded carbon (a-tC) films with hardness and stiffness near that of diamond. Using pulsed-laser deposition, thin a-tC films (0.1{endash}0.2 {mu}m) were deposited at room temperature. The intrinsic stress in these films (6{endash}8 GPa) was relieved by a short (2 min) anneal at 600{degree}C. Raman and electron energy-loss spectra from single-layer annealed specimens show only subtle changes from as-grown films. Subsequent deposition and annealing steps were used to build up thick layers. Films up to 1.2 {mu}m thick have been grown that are adherent to the substrate and have low residual compressive stress ({lt}0.2GPa). The values of hardness and modulus determined directly from an Oliver{endash}Pharr analysis of nanoindentation experimental data were 80.2 and 552 GPa, respectively. We used finite-element modeling of the experimental nanoindentation curves to separate the {open_quotes}intrinsic{close_quotes} film response from the measured substrate/film response. We found a hardness of 88 GPa and Young{close_quote}s modulus of 1100 GPa. From these fits, a lower bound on the compressive yield stress of diamond ({approximately}100GPa) was determined. {copyright} {ital 1997 American Institute of Physics.}
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 565550
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 26 Vol. 71; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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