Abstract: A method of fabricating a polycrystalline CVD synthetic diamond wafer is disclosed. A first polycrystalline CVD synthetic diamond wafer is grown using a CVD process to a first thickness on a substrate. A second smaller wafer is cut from the polycrystalline CVD synthetic diamond wafer. The second smaller wafer is located on a carrier, and further polycrystalline CVD synthetic diamond material is grown on the second smaller wafer to a second thickness to give a polycrystalline CVD synthetic diamond material having a total thickness of the combined first and second thicknesses.

Abstract: A polycrystalline CVD synthetic diamond material is provided that has an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of between 1700 and 2400 Wm?1K?1, a thickness of at least 2.5 mm and a visible transmittance through the thickness of the polycrystalline CVD synthetic diamond of at least 25%. A wafer comprising the material is also provided, wherein at least 70% of a total area of the wafer has the properties of the polycrystalline CVD synthetic diamond material. A method for fabricating the wafer is also disclosed.

Abstract: A method of fabricating a CVD synthetic diamond material, the method comprising providing a compacted diamond carrier material consisting of compacted non-intergrown diamond particles substantially free of a second phase, and growing CVD synthetic diamond material on a surface of the compacted diamond carrier material. Composite diamond bodies made by the method are also described.

Abstract: A method of fabricating a polycrystalline CVD synthetic diamond wafer is disclosed. A first polycrystalline CVD synthetic diamond wafer is grown using a CVD process to a first thickness on a substrate. A second smaller wafer is cut from the polycrystalline CVD synthetic diamond wafer. The second smaller wafer is located on a carrier, and further polycrystalline CVD synthetic diamond material is grown on the second smaller wafer to a second thickness to give a polycrystalline CVD synthetic diamond material having a total thickness of the combined first and second thicknesses.

Abstract: A polycrystalline CVD synthetic diamond material is provided that has an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of between 1700 and 2400 Wm?1K?1, a thickness of at least 2.5 mm and a visible transmittance through the thickness of the polycrystalline CVD synthetic diamond of at least 25%. A wafer comprising the material is also provided, wherein at least 70% of a total area of the wafer has the properties of the polycrystalline CVD synthetic diamond material. A method for fabricating the wafer is also disclosed.

Abstract: A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 Wm?1K?1, the method comprising: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 mm to 5.0 mm; introducing microwaves into the CVD reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is in a range 2.5 to 4.5 W mm?2; introducing process gas into the CVD reactor wherein the process gas within the CVD reactor comprises a nitrogen concentration in a range 600 ppb to 1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration in a range 0.5% to 3.

Abstract: A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 Wm?1K?1, the method comprising: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 mm to 5.0 mm; introducing microwaves into the CVD reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is in a range 2.5 to 4.5 W mm?2; introducing process gas into the CVD reactor wherein the process gas within the CVD reactor comprises a nitrogen concentration in a range 600 ppb to 1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration in a range 0.5% to 3.