摘要
A three-dimensional nanostructure of carbon material similar to a desert rose stone, named the carbon nano-flake ball, was fabricated by a single-step microwave plasma chemical vapor deposition process. Silicon substrate pretreated with different methods was used to grow carbon nano-flake balls and to control their coverage ratio. The dimension of single carbon nano-flake ball was found to be within 10 μm and it was constructed from multiple nano-scale-thickness flakes at angles. In turn, the nano-scale-thickness flakes were composed of a sandwich-structured composite, which contained a diamond core covered by graphite. The width and length of separate flakes can exceed 1 μm. The measurement of field emission properties revealed that the turn-on electric field can be as low as 2.13 V/μm, which is better than a conventional diamond film. In addition, the growth mechanism of carbon nano-flake balls was proposed. The carbon species (CH, C 2 ) formed a diamond cluster at the defects on the surface of silicon substrate or spots where Fe-based catalyst located. It was discovered that the deposition temperature and CN specie are the key factors to grow carbon nano-flake ball.