Deterministic Arrays of Epitaxially Grown Diamond Nanopyramids with Embedded Silicon‐Vacancy Centers

Abstract

In contrast to the more common nitrogen-vacancy (NV) center in diamond, the SiV possesses bright narrow band and spectrally stable optical transition concentrated (70% of the fluorescence) in its zero phonon line (ZPL) protected by inversion symmetry, even at room temperature. [4,5] Despite these attractive characteristics, some properties hinder the SiV applicability: short coherence times (nanosecond scale), limited mainly by coupling to the thermal acoustic phonon bath [6] and low extraction efficiency from the high-index diamond substrate. Different methods for mitigating these issues have been investigated in recent years, [1,[7][8][9][10] but currently there is no apparent approach to exploit the SiV superb optical properties at room temperature and at the same time to increase its photon outcoupling without compromising its optical quality and coherence. The use of nanodiamonds or nanostructures prepared by a top-down approach can mitigate the issue of total internal reflection within the diamond, but at the same time may introduce additional decoherence [11] and optical instability mechanisms attributed to poor surface quality (surface defects containing spins, charge traps, nondiamond phases, surface termination of atoms and groups [12] ) as a result of the synthesis or structuring process. The SiVs can be formed in the diamond host via ion implantation of silicon ions [1,13] or by introducing silicon atoms from a solid or gas precursor during the growth stage of diamond layers. [14,15] The latter is considered to better preserve the quality of the diamond layer by avoiding implantation damages and promoting a smaller amount of vacancy clusters and nonradiative sites which can otherwise hinder the SiV applicability. Herein, the ability to sculpt nanostructures by a bottom-up approach enables the creation of higher quality complex structures that are not accessible via top-down fabrication techniques. [16][17][18] In particular, this concerns the fabrication of highly confined and deterministic nanostructures hosting an atom-like system that maintain the original substrate quality -a critical prerequisite for quantum information and sensing applications. Here, we present a robust and deterministic template-assisted bottom-up process for the creation of high-quality nanoscale diamond pyramids incorporating SiVs.The negatively charged silicon-vacancy center (SiV) in diamond is a potential high-quality source of single-indistinguishable photons for quantum information processing and quantum electrodynamics applications. However, when embedded in bulk diamond, this emitter suffers from both, relatively low extraction efficiency attributed to total internal reflection as well as nondeterministic location. On the other hand, its implementation in nanodiamonds is impeded by optical dephasing owing to their degraded surface quality. Here a robust and deterministic template-assisted bottom-up process for the creation of high-quality diamond nanopyramids incorporating SiVs is reported. This method employs a predefi...

Single crystal diamond pyramids for applications in nanoscale quantum sensing

“…8). Our simulations for the case of NV − concentration near the pyramid apex yield a top and bottom-side collection factor ξ bottom = 0.20 and ξ top =0.058, whose ratio ξ bottom /ξ top = 3.48 is in reasonable agreement with our experimental finding of ξ bottom /ξ top ∼ 3.2 and previous reports on similar structures[16,27].…”

Nanoscale sensing based on nitrogen vacancy centers in single crystal diamond and nanodiamonds: achievements and challenges

“…Current state of the art examples of successful nanofabrication performed on diamond as an example of nanowaveguides and nanocavities. Reproduced with permission from[63,75,76,76,77].…”

Chemical vapour deposition diamond single crystals with nitrogen-vacancy centres: a review of material synthesis and technology for quantum sensing applications

“…Depending on the growth conditions, the shape of those pyramidal features can be varied according to the relative growth rates of different crystalline planes. This additional step can thus increase the concentration and localization of active colour centres [225][226][227] which can be useful to create quantum sensors or single photon sources based on this material [228]. In a similar way, fabrication of p-n electronic devices has been achieved by locally growing phosphorous doped layers on patterned diamond single crystals [229].…”