Growth of mirror-like ultra-nanocrystalline diamond (UNCD) films by a facile hybrid CVD approach**Development of CVD ultra-nanocrystalline diamond films and related high-precision machining products (International S&T Cooperation, No. S2015ZR1100).

Abstract

In this study, growth of mirror-like ultra-nanocrystalline diamond (UNCD) films by a facile hybrid CVD approach was presented. The nucleation and deposition of UNCD films were conducted in microwave plasma CVD (MPCVD) and direct current glow discharge CVD (DC GD CVD) on silicon substrates, respectively. A very high nucleation density (about 1 × 1011 nuclei cm−2) was obtained after plasma pretreatment. Furthermore, large area mirror-like UNCD films of Φ 50 mm were synthesized by DC GD CVD. The thickness and grain size of the UNCD films are 24 μm and 7.1 nm, respectively. In addition, the deposition mechanism of the UNCD films was discussed.