Studies on HPHT synthesis and N defects of N-rich B-doped diamonds

Abstract

In this paper, high-quality N-rich single crystal diamonds with different boron additive contents were synthesized in NiMnCo alloy with high Ni content by the temperature gradient growth method under HPHT (high pressure and high temperature) conditions. The C, A and N⁺ centers were present in synthetic crystals simultaneously, and the evolution of different N defects versus the boron additive contents was discussed. Infra-red absorption spectroscopy results showed that with increasing content of boron additive in the growth system, the intensity of 1332 cm⁻¹ peak related to N⁺ center (substitutional nitrogen atom with a positive charge) increased, and the concentrations of C center, A center and total N impurity decreased gradually. Moreover, the Raman results indicated higher crystallinity of N-rich B-doped diamond with increasing boron additive due to the formation of B–N bond in the lattice. Diamonds presented characterizations of p-type semiconductors with further increase in B additive content. However, the Hall mobility was extremely low due to scattering caused by abundance of N defects.