Effect of metal solvent and growth surface on boron doping efficiency and impurity incorporation in HPHT-grown diamond single crystals

To enhance boron doping efficiency and reduce metal impurities in diamonds, selecting an appropriate metal solvent is essential for producing p-type diamonds using the high-pressure high-temperature (HPHT) method. This paper presents a detailed study of the properties and characteristics of boron-doped diamond (BDD) single crystals grown using FeNi and FeCo solvents through the HPHT method. The results indicate that, with the same TiB₂ addition ratio, BDD crystals grown using FeCo solvent have a higher concentration of uncompensated boron ions, resulting in improved boron doping efficiency. Additionally, by growing BDD in the same synthesis environment (FeCo-3 wt% TiB₂) using (111) and (100) seed crystals as growth surfaces, it was found that the boron content in the crystal grown from the (100) seed crystal was higher than that in the crystal grown from the (111) seed crystal. Additionally, the crystals grown with the FeCo solvent contained fewer metal elements (Fe and Co) compared to those produced with the FeNi solvent (Fe and Ni), which supported the growth of high-quality BDD single crystals. This indicated that the choice of growth planes significantly influences the incorporation of boron in diamonds. Our findings hold significant research value for the development of high-quality p-type diamond semiconductors using the HPHT method.