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 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 vapor deposition, the microwave plasma reactor comprising: a microwave generator configured to generate microwaves at a frequency f; a plasma chamber comprising a base, a top plate, and a side wall extending from said base to said top plate defining a resonance cavity for supporting a microwave resonance mode, wherein the resonance cavity has a central rotational axis of symmetry extending from the base to the top plate, and wherein the top plate is mounted across said central rotational axis of symmetry; 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 comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use; wherein the resonance cavity is con

Abstract: A method of producing a CVD single crystal diamond layer on a substrate includes adding into a DVD synthesis atmosphere a gaseous source comprising silicon. The method can be used to mark the diamond material, for instance to provide means by which its synthetic nature can more easily be determined. It can also be exploited to generate single crystal diamond material of high color.

Abstract: A microwave plasma reactor for manufacturing a synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber (2); a substrate holder (4) 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 (12) for feeding microwaves from a microwave generator (8) into the plasma chamber; and a gas flow system (13,16) for feeding process gases into the plasma chamber and removing them therefrom, wherein the microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber comprises: an annular dielectric window (18) formed in one or several sections; a coaxial waveguide (14) having a central inner conductor (20) and an outer conductor (22) for feeding microwaves to the annular dielectric window; and a waveguide plate (24) comprising a plurality of apertures (28) disposed in an annular configuration with a plurality of arms

Abstract: A microwave plasma reactor for manufacturing a synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber (2); a substrate holder (4) 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 (12) for feeding microwaves from a microwave generator (8) into the plasma chamber; and a gas flow system (13,16) for feeding process gases into the plasma chamber and removing them therefrom, wherein the microwave coupling configuration for feeding microwaves from the microwave generator into the plasma chamber comprises: an annular dielectric window (18) formed in one or several sections; a coaxial waveguide (14) having a central inner conductor (20) and an outer conductor (22) for feeding microwaves to the annular dielectric window; and a waveguide plate (24) comprising a plurality of apertures (28) disposed in an annular configuration with a plurality of arms

Abstract: A method of producing CVD diamond having a high color, which is suitable for optical applications, for example. The method includes adding a gaseous source comprising a second impurity atom type to counter the detrimental effect on colour caused by the presence in the CVD synthesis atmosphere of a first impurity atom type. The described method applies to the production of both single crystal diamond and polycrystalline diamond.

Abstract: A method of producing CVD diamond having a high colour, which is suitable for optical applications, for example. The method includes adding a gaseous source comprising a second impurity atom type to counter the detrimental effect on colour caused by the presence in the CVD synthesis atmosphere of a first impurity atom type. The described method applies to the production of both single crystal diamond and polycrystalline diamond.