Boron-doped diamond growth and characteristics in a Ni-based alloy catalyst system at HPHT conditions

Boron-doped diamond (BDD) single crystals were synthesized with different boron additions using the temperature gradient method (TGM) in the pressure and temperature ranges of 5.6–6.0 GPa and 1360–1410 °C, respectively. The samples were characterized in terms of morphology, crystal quality and performance. The boron addition to the diamond gradually changed the crystal color from yellow-green to opaque black, and caused a large number of growth streaks and pits on the crystal surface. The boron increment in the system reduced the quality of the synthesized diamond. In the Raman spectra of diamond, additional bands appeared at 480, 588, 920, 1042 and 1220 cm−1, indicating the high boron concentration in diamond. The X-ray photoelectron spectroscopy (XPS) results confirmed that boron entered the diamond lattice in the form of BC and BO bonds. The Hall measurement results of synthesized crystals showed that the highest carrier concentration of the synthesized BDD reached 4.51 × 1017 cm−3.