High-pressure and high-temperature treatment of N-rich B-doped diamonds

Abstract

N-rich B-doped single crystal diamonds with different boron additive contents were annealed in conditions of 2.5 GPa and 2300 K. The FTIR spectra of the as-grown and annealed crystals indicate that the incorporation of boron impurity decreases the efficiency of the C centers aggregating into the A centers during the process of HPHT annealing treatment. The N⁺ center concentration in the N-rich B-doped crystals slightly increased, and the C–H pairs were all annealed after the HPHT treatment. The Raman spectra of the annealed crystals show narrower FWHM of the 1332 cm⁻¹ peak, suggesting that better crystallinity was achieved by this HPHT treatment. Meanwhile, the Hall effect measurements indicated that the HPHT treatment strengthened the compensation between the N impurity and uncompensated B acceptors; thus, the carrier concentration decreased and the resistivity increased.