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

Abstract

The silicon-vacancy (SiV) color center in diamond is a solid-state single photon emitter and spin quantum bit suited as a component in quantum devices. Here, we show that SiV centers in nanodiamonds exhibit a strongly inhomogeneous distribution with regard to the center wavelengths and linewidths of the zero-phonon-line (ZPL) emission at room temperature. We find that the SiV centers separate in two clusters: one group exhibits ZPLs with center wavelengths within a narrow range ≈730-742 nm and broad linewidths between 5 and 17 nm, whereas the second group comprises a very broad distribution of center wavelengths between 715 and 835 nm, but narrow linewidths from below 1 up to 4 nm. Supported by ab initio Kohn-Sham density functional theory calculations we show that the ZPL shifts of the first group are consistently explained by strain in the diamond lattice. Further, we suggest, that the second group showing the strongly inhomogeneous distribution of center wavelengths might be comprised of a new class of silicon-related defects. Whereas single photon emission is demonstrated for defect centers of both clusters, we show that emitters from different clusters show different spectroscopic features such as variations of the phonon sideband spectra and different blinking dynamics.

Spectroscopic investigations of negatively charged tin-vacancy centres in diamond

“…A reason for this could be a different phonon coupling for different types and strengths of strain in the two samples, resulting in differing phonon broadening. Similar room temperature distributions of ZPL centre wavelengths and linewidths were reported for SiV − centres in nanodiamonds, were it is common that large strain is exerted on the colour centres [11,32].…”

Building Blocks for Quantum Network Based on Group‐IV Split‐Vacancy Centers in Diamond

“…The principal axis of XV center, that is, threefold rotation axis (C3) of D 3d point group, is aligned along <111> crystal axis of the diamond, as predicted by ab initio calculations based on density functional theory, which has been experimentally verified by spectroscopy and polarization measurements on single SiV − centers hosted in a low‐strain environment. In comparison, within a strongly strained environment (e.g., in nanodiamond), the lattice distortion can be so significant that the high symmetry of XV centers’ structure can no longer be maintained but reduces to lower ones, such as C 2 and D 2 point groups, which are often accompanied by a broad inhomogeneous distribution of ZPL center wavelengths and linewidths …”

Observation of Binary Spectral Jumps in Color Centers in Diamond

“…Indeed, some strained emitters do show broad inhomogeneous distribution and do not always exhibit the four characteristic lines. [ 21 ] Additionally, the closeness of the fluorescence lifetime to that of GeV centers found within the same sample [ 18 ] also supports this argument. However, we cannot exclude a color center that has been already present in the diamond and activated upon annealing.…”

“…Additionally, density functional theory (DFT) calculations on SiV color centers [ 21,28 ] show that it is thermodynamically stable to have Si complexes like SiV2, SiV:H1, etc., in diamond, which usually exhibit a wide range of redshifted emissions as comparing to conventional SiV ‐ color centers. This is consistent with our observations here that all three emitters display emissions at wavelengths longer than the conventional GeV ‐ color centers.…”

“…For example, some types of these color centers exhibit a small spectral diffusion with a relatively narrow linewidth, thanks to its low sensitivity to the local electric‐field fluctuations [ 20 ] while the others show a wide distribution of emission wavelengths which is accompanied by a clear bimodular photon statistics. [ 21 ] So far, a complete understanding of these phenomena is still lacking.…”