Synthetic CVD diamond

A chemical vapour deposition (CVD) method for synthesizing diamond material on a substrate in a synthesis environment, said method comprising:

• providing the substrate;
• providing a source gas;
• dissociating the source gas;
• and
• allowing homoepitaxial diamond synthesis on the substrate;
• wherein the synthesis environment comprises nitrogen at an atomic concentration of from about 0.4 ppm to about 50 ppm;
• and
• and wherein the source gas comprises:
• a) an atomic fraction of hydrogen, Hf, from about 0.40 to about 0.75;
• b) an atomic fraction of carbon, Cf, from about 0.15 to about 0.30;
• c) an atomic fraction of oxygen, Of, from about 0.13 to about 0.40;
• wherein HfCfOf=1;
• wherein the ratio of atomic fraction of carbon to the atomic fraction of oxygen, Cf:Of, satisfies the ratio of about 0.45:1<Cf:Of<about 1.25:1;
• wherein the source gas comprises hydrogen atoms added as hydrogen molecules, H2, at an atomic fraction of the total number of hydrogen, oxygen and carbon atoms present of between 0.05 and 0.40;
• and
• wherein the atomic fractions Hf, Cf and Of are fractions of the total number of hydrogen, oxygen and carbon atoms present in the source gas.