Characteristics of Diamond Deposition on Al2O3, Diamond-like Carbon, and Q-Carbon
We have conducted a comparative study on the deposition of diamond thin film on uncoated
Al2O3, diamond-like carbon (DLC, grown by pulsed laser deposition) film-coated Al2O3,
and Q-carbon (fabricated by nanosecond pulsed laser annealing)-coated Al2O3 substrates
by hot filament chemical vapor deposition (HFCVD). Scanning electron microscopy shows
that the continuous large-area diamond thin film can be grown on the Q-carbon/Al2O3
substrate, whereas the deposition of diamond on DLC/Al2O3 or uncoated Al2O3 substrates …
Al2O3, diamond-like carbon (DLC, grown by pulsed laser deposition) film-coated Al2O3,
and Q-carbon (fabricated by nanosecond pulsed laser annealing)-coated Al2O3 substrates
by hot filament chemical vapor deposition (HFCVD). Scanning electron microscopy shows
that the continuous large-area diamond thin film can be grown on the Q-carbon/Al2O3
substrate, whereas the deposition of diamond on DLC/Al2O3 or uncoated Al2O3 substrates …
We have conducted a comparative study on the deposition of diamond thin film on uncoated Al2O3, diamond-like carbon (DLC, grown by pulsed laser deposition) film-coated Al2O3, and Q-carbon (fabricated by nanosecond pulsed laser annealing)-coated Al2O3 substrates by hot filament chemical vapor deposition (HFCVD). Scanning electron microscopy shows that the continuous large-area diamond thin film can be grown on the Q-carbon/Al2O3 substrate, whereas the deposition of diamond on DLC/Al2O3 or uncoated Al2O3 substrates gives cluster-like/patches of discontinuous diamond thin film formation. Raman spectroscopy of the diamond on Q-carbon/Al2O3 shows a considerably small residual stress (1.7 GPa) compared to the diamond on DLC/Al2O3 (3.1 GPa) or diamond on the uncoated Al2O3 (3.9 GPa) substrate. The nondiamond content in the diamond crystals on Q-carbon-coated Al2O3 is found to be only 0.12%, which is about 2.5 and 3.5 times less than that of diamond on DLC-coated Al2O3 and uncoated Al2O3, respectively. Consistent with the Raman analysis, the X-ray diffraction analysis shows the crystalline growth of the HFCVD diamond on Q-carbon/Al2O3 with relatively small in-plane stress compared to the diamond film on the other two systems. We propose that the high density of diamond tetrahedron in the Q-carbon structure provides a good platform for diamond growth with a very high nucleation density over 109 cm–2 and can act as a seed layer for diamond growth without cracking or delamination over the surface of the substrate. The optically transparent high-quality diamond film on Q-carbon-coated Al2O3 showed better adhesion compared to that on DLC-coated Al2O3 and uncoated Al2O3, as measured by a simple scotch tape test. These results open a path toward the fabrication of large-area high-quality diamond films on an optically transparent substrate for commercial applications.
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