Chemical vapour deposition (CVD) process for growing mono-crystalline gem grade diamonds

摘要

A method of forming mono-crystalline gem grade diamond by chemical vapour deposition is disclosed, wherein the method comprises the steps of:(a) providing at least one diamond seed;(b) exposing the seed to conditions for growing diamond by chemical vapour deposition, including supplying reaction gases that include a carbon-containing gas for growing diamond and include a nitrogen-containing gas; and(c) controlling the quantity of nitrogen-containing gas relative to other gases in the reaction gases such that diamond is caused to grow by step-growth without defects and graphitic inclusions;wherein the chemical vapour deposition comprises maintaining the seed at a temperature in the range of 750 to 1200 Deg. C and at a reduced pressure in the range of 120 to 160 mbar; and wherein the quantity of nitrogen-containing gas in the reaction gases is in the range of 0.0001 to 0.02 vol% and further including diborane in the reaction gases; and wherein the nitrogen-containing gas may be selected from anyone or more of the group comprising nitrogen in hydrogen, nitrogen in oxygen, nitrogen in helium, nitrogen in nitrous oxide or nitrogen with diborane; and wherein the chemical vapour deposition occurs in the presence of microwave plasma generated by a magnetron operating at 6000 Watt and at 2.45 GHz and with hydrogen in the reactions gases.