1. Principle: Use microwave to excite the reactive gas to form plasma. The frequency of microwave is generally 2.45GHz. Under the action of microwave, the electrons in the reactive gas obtain energy and collide with the gas molecules to ionize and decompose, forming a plasma region. In the plasma, carbon-containing active particles are deposited on the single crystal diamond substrate and epitaxial growth, and single crystal diamond flakes are gradually formed.
2. Equipment Composition: It is mainly composed of microwave generator, microwave transmission system, reaction chamber, gas supply system, vacuum system, temperature control system and plasma diagnosis system. The microwave generator generates high power microwaves; the microwave transmission system efficiently transmits the microwaves to the reaction chamber; the reaction chamber provides space for plasma generation and diamond growth; the gas supply and vacuum systems are similar to HFCVD; the temperature control system accurately controls the temperature of the substrate; the plasma diagnostic system is used to monitor the parameters of the plasma, such as the electron density, temperature, etc., in order to optimize the growth conditions.
3. Advantages and disadvantages: the advantages are that the plasma parameters can be precisely controlled, the growth environment is pure, high-quality, large-area single-crystal diamond flakes can be prepared, and the growth rate is relatively high, up to tens of microns per hour. Disadvantages are complex equipment, high cost, high technical requirements for operators, and microwave equipment maintenance and operation costs are also high.
DC Arc Plasma Jet Chemical Vapor Deposition (DC Arc Plasma Jet CVD)
1. Principle: A high-temperature plasma jet is formed between electrodes by DC arc discharge. The arc voltage is generally in the tens of volts to hundreds of volts, and the current can be up to several hundred amperes. The reactive gas is rapidly heated and decomposed when passing through the plasma jet area, and the resulting carbon-containing reactive species are deposited on the substrate surface and grow into single crystal diamond flakes.
2. Composition of the equipment: It mainly includes DC power supply, arc generator, reaction chamber, gas supply system, vacuum system, cooling system and substrate moving device. The DC power supply provides stable arc discharge energy; the arc generator produces high-temperature plasma jet; the reaction chamber accommodates the plasma jet and growth process; the gas supply and vacuum system maintains the reaction environment; the cooling system is used to cool the electrodes and the reaction chamber; the substrate moving device can realize the growth of the substrate in different positions, which is conducive to the growth of uniform large-area single-crystal diamonds.
3. Advantages and disadvantages: the advantage is that the deposition rate is very high, up to hundreds of microns per hour, suitable for rapid preparation of thicker single crystal diamond flakes. The disadvantage is that the stability of the equipment is poor, the unevenness of the plasma jet is easy to lead to the growth of diamond quality is not stable, and the equipment operation process will produce large noise and electromagnetic interference, the working environment has certain requirements
