Indirect overgrowth as a synthesis route for superior diamond nano sensors

Abstract

The negatively charged nitrogen-vacancy ($$\hbox {NV}^{-}$$ NV - ) center shows excellent spin properties and sensing capabilities on the nanoscale even at room temperature. Shallow implanted $$\hbox {NV}^{-}$$ NV - centers can effectively be protected from surface noise by chemical vapor deposition (CVD) diamond overgrowth, i.e. burying them homogeneously deeper in the crystal. However, the origin of the substantial losses in $$\hbox {NV}^{-}$$ NV - centers after overgrowth remains an open question. Here, we use shallow $$\hbox {NV}^{-}$$ NV - centers to exclude surface etching and identify the passivation reaction of NV to NVH centers during the growth as the most likely reason. Indirect overgrowth featuring low energy (2.5–5 keV) nitrogen ion implantation and CVD diamond growth before the essential annealing step reduces this passivation phenomenon significantly. Furthermore, we find higher nitrogen doses to slow down the NV–NVH conversion kinetics, which gives insight into the sub-surface diffusion of hydrogen in diamond during growth. Finally, nano sensors fabricated by indirect overgrowth combine tremendously enhanced $$T_2$$ T 2 and $$T_2^*$$ T 2 ∗ times with an outstanding degree of depth-confinement which is not possible by implanting with higher energies alone. Our results improve the understanding of CVD diamond overgrowth and pave the way towards reliable and advanced engineering of shallow $$\hbox {NV}^{-}$$ NV - centers for future quantum sensing devices.

Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond

“…-2 E g transition, overlapped with the experimental PL signal from the Mg color center (experimental data is from ref. 11 ).…”

“…Moreover, near-surface NV(−) centers (needed for quantum sensing) are unstable to the commonly used types of surface termination. This compromises the fidelity and also reduces the spin-coherence time compared with their bulk counterparts, which in turn affects the spectral resolution 11 . Furthermore, to enable applications in bioimaging and quantum communication, longer wavelengths are typically needed than the zero-phonon line (ZPL) of the lowest optically allowed transition at 637 nm (1.945 eV) 12 .…”

Power-law scaling of correlations in statistically polarised nano-NMR

“…All experiments are carried out with an isotopically enriched (99.999 % 12 C) diamond sample grown by chemical vapour deposition. The diamond substrate with natural abundance of 13 C was equipped with a 99.999 % 12 C enriched homoepitaxially grown diamond film with a thickness of about 150 nm in a home-built plasma enhanced chemical vapour deposition growth reactor [32,33,45] using 99.999 % enriched 12 CH 4 gas (Cambridge Isotope Laboratories) at a concentration of 0.2 % with respect to hydrogen.…”

Fabrication of $^{15}\textrm{NV}^{-}$ centers in diamond using a deterministic single ion implanter

“…Such short coherence stems from the proximity to the diamond surface, where a variety of paramagnetic fluctuators might be present. It is possible to overcome these effects by using differently doped diamond as implantation material [36] or the recently reported so-called indirect overgrowth technique [37]. Another explanation for short coherence times might be coupling to highly concentrated neutral-charged substitutional nitrogen (P1 center) in close proximity of the generated NV [38].…”