Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition includes a microwave generator configured to generate microwaves at a frequency f, a plasma chamber that defines a resonance cavity for supporting a microwave resonance mode, a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber, a gas flow system for feeding process gases into the plasma chamber and removing them therefrom, and a substrate holder disposed in the plasma chamber and having a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use. The resonance cavity is configured to have a height that supports a TM011 resonant mode at the frequency f and is further configured to have a diameter that satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor includes a plasma chamber, a substrate holder, a microwave coupling configuration for feeding microwaves into the plasma chamber, and a gas flow system for feeding process gases into the plasma chamber and removing them therefrom. The gas flow system includes a gas inlet array having a plurality of gas inlets for directing the process gases towards the substrate holder. The gas inlet array includes at least six gas inlets disposed in a substantially parallel or divergent orientation relative to a central axis of the plasma chamber.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition includes a microwave generator configured to generate microwaves at a frequency f, a plasma chamber that defines a resonance cavity for supporting a microwave resonance mode, a microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber, a gas flow system for feeding process gases into the plasma chamber and removing them therefrom, and a substrate holder disposed in the plasma chamber and having a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use. The resonance cavity is configured to have a height that supports a TM011 resonant mode at the frequency f and is further configured to have a diameter that satisfies the condition that a ratio of the resonance cavity height/the resonance cavity diameter is in the range 0.3 to 1.0.

Abstract: Disclosed herein are methods of manufacturing synthetic CVD diamond material including orienting and controlling process gas flow in a microwave plasma reactor to improve performance. The microwave plasma reactor includes a gas flow system with a gas inlet comprising one or more gas inlet nozzles disposed opposite the growth surface area and configured to inject process gases towards the growth surface area. The method comprises injecting process gases towards the growth surface area at a total gas flow rate equal to or greater than 500 standard cm3 per minute wherein the process gases are injected into the plasma chamber through the one or more gas inlet nozzles with a Reynolds number in a range 1 to 100.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber; a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber; and a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; wherein the microwave plasma reactor further comprises an electrically conductive plasma stabilizing annulus disposed around the substrate holder within the plasma chamber.

Abstract: A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber; a substrate holder disposed in the plasma chamber for supporting a substrate on which the synthetic diamond material is to be deposited in use; a microwave coupling configuration for feeding microwaves from a microwave generator into the plasma chamber; and a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; wherein the gas flow system comprises a gas inlet nozzle array comprising a plurality of gas inlet nozzles disposed opposite the substrate holder for directing process gases towards the substrate holder, the gas inlet nozzle array comprising: at least six gas inlet nozzles disposed in a substantially parallel or divergent orientation relative to a central axis of the plasma chamber; a gas inlet nozzle number density equal to or greater than 0.

Abstract: The present invention provides a solid diamond electrode, a reactor, in particular a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond, and methods in which the reactors are used.

Abstract: The present invention provides a solid diamond electrode, a reactor, in particular a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond, and methods in which the reactors are used.

Abstract: The present invention provides a solid diamond electrode, a reactor, in particular a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond, and methods in which the reactors are used.