Featured article: Long optical coherence times of shallow-implanted, negatively charged silicon vacancy centers in diamond

Universität Ulm

The creation of single, negatively charged silicon vacancy centers (SiV-) in well-defined diamond layers close to the host surface is a crucial step for the development of diamond-based quantum optics devices with many applications in nanophotonics, quantum sensing or quantum information science. The experimental capabilities established in our group allow both ultrapure growth of single-crystalline diamond substrates as well as focused ion implantation and high temperature annealing of single defects (NV-, SiV-) in diamond featuring tailored production recipes for many applications in diamond color center research. This featured article presents results on the successful creation of shallow (10 nm below the surface), stable, single SiV- centers in diamond using low energy Si+ ion implantation with subsequent high temperature annealing at 1500 °C [Fig.1(a)]. Transition linewidths down to 99 MHz [Fig.1(b)] and narrow inhomogeneous distributions with spectrometer limited inhomogeneous broadening around 30 GHz [Fig.1(c)] prove the exceptional performance of our experimental setups and processing techniques. Furthermore, we achieved a reduction of homogeneous linewidths by a factor of 2 after removing subsurface damage using oxygen plasma processing. These results not only give insight in the formation process of SiV- centers, but also indicate a favorable processing method to fabricate shallow single quantum emitters in diamond perfectly suited for coupling to nanostructures on the diamond surface.

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Appl. Phys. Lett. 116, 064001 (2020);

Figure 1: (a) Room temperature spectrum with ZPL at 737 nm. Inset shows annealing process. (b) Narrowest PLE Spectrum of transition C. (c) Inhomogeneous distribution with spectrometer limited linewidths