Synthesis of Thick Diamond Film by Direct Current Hot-Cathode Plasma Chemical Vapor Deposition

The method of direct current hot-cathode plasma chemical vapour deposition method is established. A long-time stable glow discharge at large discharge current and high gas pressure has been achieved by using a hot cathode in the temperature range from 1100°C to 1500°C and nonsymmetrical configuration of the poles, in which the diameter of cathode is larger than that of anode. High quality thick diamond films in diameter of 40-50 mm and thickness of 0.5-4.2 mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates of 5-10μm/h. Most of the thick diamond films have thermal conductivities of 10-12W/K.cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and used as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved.