Synthesis of thick diamond films by direct current hot-cathode plasma chemical vapour deposition

The method of direct current hot-cathode plasma chemical vapour deposition has been 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 1100degreesC to 1500degreesC and nonsymmetrical configuration of the poles, in which the diameter of the cathode is larger than that of anode, High-quality thick diamond films, with a diameter of 40-50mm and thickness of 0.5-4.2mm, have been synthesized by this method. Transparent thick diamond films were grown over a range of growth rates between 5-10 mum/h. Most of the thick diamond films have thermal conductivities of 10-12 W/K(.)cm. The thick diamond films with high thermal conductivity can be used as a heat sink of semiconducting laser diode array and as a heat spreading and isolation substrate of multichip modules. The performance can be obviously improved.