Complexes of silicon, vacancy, and hydrogen in diamond: A density functional study

Abstract

Paramagnetic luminescent point defects in diamond are increasingly important candidates for quantum information processing applications. Recently, the coherent manipulation of single silicon-vacancy defect spins has been demonstrated in chemical vapor deposited diamond samples where silicon may be introduced as a contamination in the growth process. Hydrogen impurity may simultaneously enter diamond too and form complexes with silicon-vacancy defects. However, relatively little is known about these complexes in diamond.Here we report plane-wave supercell density functional theory results on various complexes of silicon vacancy and hydrogen in diamond. We found a family of complexes of silicon, vacancies, and hydrogen atoms that are thermally stable in diamond with relatively low formation energies that might form yet unobserved or unidentified silicon-related defects. These complexes often show infrared optical transitions and are paramagnetic. We tentatively assign one of these complexes to a recently reported but yet unidentified infrared absorber center. We show that this center has a metastable triplet state and might exhibit a spin-selective decay to the ground state, thus it is an interesting candidate for quantum information processing applications. We also discuss here methodology aspects of calculating hyperfine parameters and intradefect level excitations in systems with notoriously complex electron states within hybrid density functional approach. We also demonstrate that a simplified approach using ab initio data can be very powerful to predict the relative intensities of the phonon replica associated with quasilocal vibration modes in the photoexcitation spectrum.

Strongly inhomogeneous distribution of spectral properties of silicon-vacancy color centers in nanodiamonds

“…Together with the observed existence of a gap between groups H and V this points towards a separate fluorescent defect complex containing silicon, e.g. the association of SiV centers with a further nearby defect, such as a vacancy, or a modified SiV complex such as SiV:H [58].…”

Characterization of oxygen defects in diamond by means of density functional theory calculations

“…Silicon-hydrogen complexes were also found in diamond 56,64 . Here, we consider complex formation of hydrogen with substitutional oxygen and oxygenvacancy defects.…”

“…In the previous (semi)local DFT studies the highly correlated ground state was not considered for O S (0) 31,33 . We showed for SiV-related defects in diamond 56 that spinpolarized hybrid density functional Fig. 6 with their corresponding labels where the zz, yy and xx components are shown by blue, green and red arrows, respectively.…”

“…7(b) we obtain the zerophonon-line energy of 1.39 eV. We assume an accuracy of about 0.2 eV of this procedure based on our experience 56 . The shelving triplet state has about 0.04 eV higher energy than that of the ground state singlet.…”

“…Therefore, we study the shelving and excited states of O S (0) in detail. We follow a similar methodology as was explained for SiV 2 :H(−) defect in diamond 56 . The triplet state can be described as the occupation of a 1 and b 1 states by parallel spins ( 3 B 1 state) whereas the optically allowed 1 B 1 state was constructed from constrained occupation of symmetric orbitals [see Fig.…”