Multiple growth and characterization of thick diamond single crystals using chemical vapour deposition working in pulsed mode

In this paper, the fast growth of three thick diamond single crystals using the chemical vapour deposition (CVD) method working in a pulsed mode is reported. After 48 h, a total of half a carat of uncoloured synthetic diamond was obtained. These crystals, exhibiting thicknesses of 430, 570 and 900 μm, were then thoroughly analysed by a wide range of characterization techniques, such as Raman spectroscopy, UV and IR absorption, photoluminescence (PL) and cathodoluminescence (CL). All three samples turned out to be of relatively high quality but small differences in purity and quality could be detected. These appeared to be directly related to the slight inconsistence of the substrate temperature during growth that ranged from 800 to 900 °C due to non-uniformity in the radial distribution of gas temperature. A higher contamination by residual nitrogen impurities has been evidenced for the two samples that were grown with the lowest temperature as confirmed by the PL and UV absorption spectra, as well as a lower free excitonic emission in CL. Finally a 900 °C growth temperature was shown to be more favourable to good quality and fast growth rate.