25 March 2021

Trace impurities measurements from LDetek ensure quality of synthetic diamonds ‘grown’ in the lab

Trace impurities detection expert, LDetek, has developed a complete turnkey solution for producing synthetic diamonds. Using the combination of gas chromatograph with integrated stream selection and gas dilution, operators can speed up the process of growing high-quality cultured diamonds using chemical vapor deposition.

Large scale synthetic diamond production uses the high pressure and high temperature (HPHT) process as this is the most economical method to produce large quantities of synthetic diamonds. However, the chemical vapor deposition (CVD) method produces the best grade of synthetic diamond possible in a relatively short time.

CVD creates a carbon plasma over a substrate onto which the carbon atoms deposit to form diamond. It allows for better control of characteristics and properties of the diamonds but requires good control of impurities in the hydrocarbon gases used, and this is where LDetek’s trace impurities system plays a vital role.

Levels of N2 must be carefully controlled, along with trace O2 and H2O to confirm the purity of the hydrogen, methane and other additive gases.

Trace N2 from sub ppb to few hundred ppm is measured with the LDetek PlasmaDetek2 detector mounted in the MultiDetek2 gas chromatograph. Optional H2O-NH3 and O2 analysis can be added in the same instrument when required by the process. LDetek’s LDGSS stream selector system ensures the automatic switching sequence for analysis between H2/CH4 and the different additive gases, while the LDGDSA automatic dilution system can be added to accurately calibrate for gases in parts per billion.

Synthetic diamonds – also referred to as cultivated diamonds – are created all over the world and used in the same way as naturally occurring diamonds. This includes jewelry, electronics, machine and cutting tools, thermal conductors and optical materials. For industry, synthetic diamonds are less costly but valued as a highly ethical product since there is little humanitarian or environmental impact involved in their production. For jewelry, other advantages include the ability to produce shapes not possible in nature and better control over the quality of the stones.

The complete, detailed application note, which includes information on lower detection limits and chromatograms of the measurements, is available to download on ProcessSensing.com:
Trace impurities measurement for synthetic diamond grown by chemical vapor deposition (CVD)