A method of fabricating synthetic diamond material using a microwave plasma activated chemical vapour deposition technique is provided which utilizes high and uniform microwave power densities applied over large areas and for extended periods of time. Products fabricated using such a synthesis technique are described including a single crystal CVD diamond layer which has a large area and a low nitrogen concentration, and a high purity, fast growth rate single crystal CVD diamond material.

A method for making a monocrystalline structure is disclosed. The method includes depositing a first volume of a material on a substrate to create a first crystal seed and depositing a second volume of the material towards the substrate to nucleate with the first crystal seed to create a first initial epitaxial structure.

A diamond manufacturing apparatus for forming at least one diamond is provided. The diamond manufacturing apparatus comprises a growth base and an electric field device. The growth base comprises a top portion and a bottom portion opposite to each other, and the top portion has a growth surface that is concave toward the bottom portion. A plurality of electric field lines of an electric field that is generated by the electric field device are substantially perpendicular to the growth surface.

A reaction apparatus contacts a process gas on a semiconductor wafer during a wafering process. The semiconductor wafer defines a center region. The reaction apparatus includes an upper dome, a lower dome, a shaft, and a cap. The lower dome is attached to the upper dome, and the upper dome and the lower dome define a reaction chamber. The cap is positioned on the shaft within the reaction chamber for reducing heat absorbed by the center region of the semiconductor wafer. The cap is attached to a first end of the shaft. The cap includes a tube and a disc. The tube defines a tube diameter larger than a shaft diameter of the shaft. The tube circumscribes the first end of the shaft. The disc is attached to the tube and is positioned to block radiant heat from heating the center region of the semiconductor wafer.

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.

Provided is a single crystal diamond having a lowered dislocation density. The single crystal diamond (10) is provided with single crystal diamond layers (2, 3). One single crystal diamond layer (2) is formed on a diamond substrate (1) and contains point defects. The other single crystal diamond layer (3) is grown on the single crystal diamond layer (2). The single crystal diamond layers (2, 3) have a lower dislocation density than the diamond substrate.

A method of manufacturing synthetic diamond material using a chemical vapour deposition process, and a diamond obtained by such a method are described. The method comprises providing a freestanding synthetic single crystal diamond substrate wafer having a dislocation density of at least 10.sup.7cm.sup.−2. The synthetic single crystal diamond substrate wafer is located over a substrate holder within a chemical vapour deposition reactor. Process gases are fed into the reactor, the process gases including a gas comprising carbon. Crack-free synthetic diamond material is grown on a surface of the single crystal diamond substrate wafer at a temperature of at least 900° C. to a thickness of at least 0.5 mm and with lateral dimensions of at least 4 mm by 4 mm.

A composition (or an aggregate) comprising an epitaxial h-BN/BNNT structure that comprises a hexagonal boron nitride structure that is epitaxial with respect to a boron nitride nanotube structure. Also, a composition (or an aggregate) that comprises independent boron nitride nanotubes, in which a total mass percentage of independent hexagonal boron nitride and residual boron in the composition is not more than 35%. Also, a composition (or an aggregate) in which not more than 1% of independent boron nitride nanotubes and boron nitride nanotube structures have a dixie cup or bamboo defect. Also, a composition in which at least 50% of independent boron nitride nanotubes and boron nitride nanotube structures are single-wall. Also, a method of making a composition that comprises epitaxial h-BN/BNNT structures.

A method for manufacturing diamond substrate of using source gas containing hydrocarbon gas and hydrogen gas to form diamond crystal on an underlying substrate by CVD method, to form a diamond crystal layer having nitrogen-vacancy centers in at least part of the diamond crystal, nitrogen or nitride gas is mixed in the source gas, wherein the source gas is: 0.005 volume % or more and 6.000 volume % or less of the hydrocarbon gas; 93.500 volume % or more and less than 99.995 volume % of the hydrogen gas; and 5.0×10.sup.−5 volume % or more and 5.0×10.sup.−1 volume % or less of the nitrogen gas or the nitride gas, and the diamond crystal layer having the nitrogen-vacancy centers is formed. A method for manufacturing a diamond substrate to form an underlying substrate, a diamond crystal having a dense nitrogen-vacancy centers (NVCs) with an orientation of NV axis by performing the CVD.

A method of growing single crystal diamond assisted by polycrystalline diamond growth to enhance dimensions and quality of the single crystal diamond includes thermally mating a diamond seed on a top surface of a substrate holder providing a growth surface for a combination of single crystal diamond and polycrystalline diamond. A predetermined temperature difference between the diamond seed and the substrate holder during processing along with the plasma process conditions causes a single crystal diamond growth rate to be different from a polycrystalline growth rate by a predetermined amount. Process gasses are introduced, and a plasma is formed to grow both single crystal diamond and polycrystalline diamond on the growth surface so that the polycrystalline diamond grown adjacent to the single crystal diamond shields side surfaces of the growing single crystal diamond, thereby improving growth quality across the growing single crystal diamond.