Synthesis and structural characterization of highly 〈1 0 0〉-oriented {1 0 0}-faceted nanocrystalline diamond films by microwave plasma chemical vapor deposition

We report the synthesis and characterization of high-quality highly 〈1 0 0〉 oriented nanocrystalline diamond (NCD) films consisting of {1 0 0} nano-facets with a high growth rate of 2.6 μm/h. The NCD samples were grown on large (1 0 0) silicon wafers of 5.08 cm in diameter by employing CH4/H2/O2/N2 chemistries without the aid of bias for orientation, microwave power 3 kW and the substrate temperature about 700 °C using a 5 kW-type high-power microwave plasma chemical vapor deposition (CVD) system. The strong 〈1 0 0〉 preferred orientation is unambiguously demonstrated by a detailed crystallographic texture analysis and the conventional X-ray diffraction. Moreover, a detailed morphological characterization by the high-resolution scanning electron microscopy (SEM) and the atomic force microscopy (AFM), reveal that the growth surface consists of square (1 0 0) facets with an average size of about 60 nm and has a cylindrical microstructure. We demonstrate that the root-mean-square surface roughness as low as ∼15 nm, measured by AFM on 1 μm2 scan areas, can be obtained even for considerably thick (76 μm) films. The high quality of these films is confirmed by the Raman and Fourier-transformer infrared spectra. The high-quality smooth 〈1 0 0〉-oriented {1 0 0}-faceted NCD films may have high potential in mechanical, tribological and micro-electromechanical system (MEMS) applications.