Effect of B-S co-doping on large diamonds synthesis under high pressure and high temperature

Large single-crystal diamonds with n-type semiconductor were synthesized from S/B-S co-doping FeNiCo-C system under high pressure and high temperature (HPHT) in this paper. It was found that the slight variation of the additive S content had not made obvious change for the color of diamonds synthesized from FeNiCo-C system. The B-S co-doping samples became more transparent and yellow than the samples added alone by S. The analysis of X-ray photoelectron spectroscopy (XPS) spectra and Fourier transform infrared (FTIR) spectroscopy showed the presence of B and S in the obtained diamonds. The electrical properties of large diamond crystals were tested by Van der Pauw method with a four-point probe. The highest value of the hall mobility was 628.726 cm2/vs. And the lowest value of the resistivity was 9.33 × 105 Ω·cm with boron additive of 0.8 wt.% and sulfur of 2 wt.% doping to diamond which was confirmed as n-type. This work indicated that B-S co-doping to synthesize diamond crystals was a trend to promote the electrical properties of large diamond crystals.