H plasma processing triggered phase transformation from DLC to diamond nano-particles

Phase transformation from diamond-like carbon (DLC) films to amorphous carbon (a-C) encapsulated diamond nano-particles (a-DNPs) has been realized by using longtime and low power radio frequency (rf, 40–60 W) H plasma processing at 1000 K. SEM observation showed that a thin film consisted of densely packed nano-particles (NPs) was formed on the surface of DLC films after a longtime H plasma processing. The length of the NPs increased dramatically with the processing time, but the density change was negligible (~ 3 × 1011 cm− 2). Visible and UV Raman revealed that the NPs were consisted of diamond and a-C. XPS showed a processing time dependent content increase of SP3-hybridized carbon, confirming the growth of diamond during the plasma treatment. Based on previous researches, a core (diamond)-shell (a-C) structure and a two-step transforming model were proposed. We conjecture that the SP3-hybridized carbon clusters in DLC behave as the seeds for the DNP growth, and the rf H plasma treatment provides an appropriate driving force for the running of this phase transformation.

Phase transformation from DLC to amorphous carbon encapsulated diamond nano-particles.Figure optionsDownload as PowerPoint slideHighlights
► Realize the phase transformation from DLC to diamond.
► Propose a core-shell structure for the nano-particles.
► Propose a two-step growth model: isotropic growth and preferential growth.