Gem quality diamond crystals are employed as anvils in high-pressure diamond cell research. Homoepitaxial growth experiments by microwave plasma-assisted chemical vapor deposition (MPCVD) have produced 1.76 mm (diameter) by 0.65 mm (thickness) sized diamonds. We report fundamental studies on diamond growth rate and quality as a function of reactor pressure and methane concentration, in a hydrogen plasma. By varying the growth conditions, large, single crystal diamond can be produced, which is ideal for manufacturing high pressure anvils.
Traditional high pressure, high temperature (HPHT) techniques for production of synthetic diamond anvils are extremely expensive and chemical vapor deposition (CVD) provides an economically viable alternative. We report diamond growth rates up to 0.32 mg/hr, which are comparable to HPHT growth rates, and crystal quality approaching that of gem diamond. When perfected, diamond anvils produced from chemical vapor deposition methods could replace those manufactured by high pressure, high temperature synthesis.