Effect of B-O co-doping on the properties of HPHT diamond single crystals in Fe-Ni-C system

Abstract

Boron-doped diamond (BDD) is highly valued for its excellent semiconductor properties, but high boron doping levels often cause lattice distortion and degraded electrical performance. To address this challenge, boron-oxygen (B-O) co-doping was proposed as a strategy for synthesizing high-quality semiconductor diamond. B-O co-doped diamond single crystals with gradient boron concentrations were synthesized via a domestic large-volume cubic high-pressure apparatus in the Fe-Ni-C system (5.8-6.2 GPa, 1360-1440 ℃). FTIR and Raman spectroscopy confirmed successful B incorporation and high-concentration boron doping, while oxygen incorporation partially mitigated boron-induced lattice stress. X-ray photoelectron spectroscopy (XPS) verified the formation of B-O bonds and co-incorporation of B and O into the diamond lattice. Hall effect measurements showed the sample with 5 wt% B and 5 wt% Fe3O4 achieved optimal electrical properties: carrier concentration of 3.76×1018 cm-3 and resistivity of 8.15×10-1 Ω·cm. Compared to pure BDD at equivalent boron doping levels, the B-O co-doped diamonds exhibited higher carrier mobility and lower resistivity, attributed to improved crystalline quality from appropriate oxygen addition. This work clarifies the B-O synergistic mechanism, providing experimental support for optimizing co-doping processes and advancing high-performance semiconductor diamond materials.