Matchless material properties offered by diamond theoretically makes it a right fit into any technological application. Wide band of optical transmission, highest thermal conductivity, stiffness, wear resistance, and excellent electronic characteristics are some of the properties. But the usage in technological applications has been limited by the synthesis process of diamond in laboratories.
Microwave Plasma Chemical Vapor Deposition (MPCVD) method has grown to become a prominent process only in last 7-8 years despite being in practice since 80 years. MPCVD is a pure and fast diamond deposition process, hence best suited for commercial use. MPCVD creates the Single Crystal Diamond (SCD) most effectively among all other diamond deposition techniques. SCD created by this process is also the most superior and outperforms Polycrystalline diamonds, High Pressure High Temperature (HPHT) diamonds and the Earth-mined diamonds in applications like electronics.
Mined diamonds are disadvantageous due to socio-environmental and cost factors, whereas HPHT is technologically challenging than CVD grown diamonds. SCDs have been in high demand for its unique and superior properties and were being mined since a long time. There is huge demand-supply gap for SCDs. Properties like radiation hardness, high breakdown voltage, single NV (Nitrogen Vacancy) centers etc. can make certain technologies more able.
CVD technique was not used prominently to produce gem-sized diamonds until recently. Lab-grown diamonds were brought into market using HPHT technique despite being a burdensome process. HPHT Grown diamonds possess inherent impurities from catalysts. But the advancements in the MPCVD based SCD technology have caught the eyes of jewelry industry. The new Lab-grown diamond companies – Apollo diamonds, Gemesis Corp., Microwave Enterprise, IIa Technologies use CVD technique. CVD technique produces diamonds that are of high quality, colorless and sometimes even better than their mined counterparts. GIA (Gemological Institute of America) has characterized 0.5 Carat CVD technique–grown diamonds as being good as earth-mined type IIa diamonds.
Following are the properties certified by GIA for Lab-grown CVD diamonds:
- Under crossed polarizer
- Green fluorescence in long, short and ultra-short UV radiation of ‘DiamondView’
- Blue Phosphorescence at 550nm
- FTIR absorption at 1332 cm-1 and 1344 cm-1 for Ns+ and Ns0 resp.
- UV-Vis-NIR absorption band around 270 nm with sharp peaksat 271nm and 268nm due to isolated nitrogen impurity
- UV-Vis-NIR absortion double at 737nm due to [Si-V]