Working Principle of MPCVD Diamond Growth System

The MPCVD diamond growth system consists of a microwave system, cooling system, motion system, detection system, gas supply system, water supply system, and control system. Its operating principle is as follows: the microwave source efficiently converts electrical energy into microwave energy, which then passes through a series of components such as a circulator and impedance matching network before entering the resonant cavity. Within the resonant cavity, the transmission mode in the waveguide is TE10 mode. After passing through a mode converter, the microwaves resonate in the cavity in TM mode and are focused in the strong electric field above the substrate stage.

When the gas inside the chamber and the microwave input power reach a matched state, the gas is ionised into plasma under the influence of the strong electric field. Subsequently, reaction gases such as methane, nitrogen, and argon undergo thermal decomposition in the high-temperature plasma environment, producing active groups such as CH, CH, C2H2, and OH. These carbon-containing active groups react chemically on the seed crystal surface, forming sp3-hybridised diamond phase and sp2-hybridised graphite phase. Since hydrogen has a stronger etching effect on graphite than on diamond, the graphite phase is gradually consumed, promoting diamond growth.

The MPCVD method uses microwave discharge technology, which has advantages such as no metal contamination, concentrated electric field, and stable energy supply, making it highly suitable for depositing high-quality diamond. The diamond produced by this method has high purity, few defects, and physical and chemical properties highly similar to those of natural diamond, making it the preferred method for thermal, optical, and electronic applications. Additionally, by mixing relevant elemental gases during deposition, controlled doping of diamond can be achieved, making MPCVD the most advanced diamond production technology currently available.