Abstract
We report the photoluminescence characteristics of a colour centre in diamond grown by plasma-assisted chemical vapour deposition. The colour centre emits with a sharp zero-phonon line at 2.330 eV (λ=532 nm) and a lifetime of 3.3 ns, thus offering potential for a high-speed single-photon source with green emission. It displays a vibronic emission spectrum with a Huang–Rhys parameter of 2.48 at 77 K. Hanbury–Brown and Twiss measurements reveal that the electronic level structure of the defect includes a metastable state that can be populated from the optically excited state.
GENERAL SCIENTIFIC SUMMARY Introduction and background. Colour centres in diamond have in recent years demonstrated attractive properties as room temperature single-photon sources and as optically addressable spin registers for quantum spintronics applications. The most widely researched is the negatively charged nitrogen-vacancy centre which, despite displaying some exquisite quantum properties, also possesses aspects that are less 'ideal', and so a strong motivation exists to identify other colour centres in diamond that may offer alternative platforms. There are hundreds of defect absorption and emission lines catalogued for diamond, but only a small handful have been positively identified and fewer still measured as single photon emitters.
Main results. We report the characterisation of a single colour centre in ultra-pure synthetic diamond that has previously only been observed in an ensemble with many other defects present. The colour centre shows a vibronic emission spectrum with a strong and narrow zero phonon line at room temperature at a wavelength of 532 nm (see figure). Single centre measurements reveal several of its physical properties that have not previously been observed, for example a lifetime of 3 ns at room temperature, at least one metastable state coupled to the optically excited state, and a Huang–Rhys factor of 2.48 at 77 K.
Wider implications. Our results form the basis for further investigations into this defect, for instance to reveal whether it possesses an electronic spin signature that may be used in spintronics applications, and to identify its molecular structure so that more can be understood about the physics that underpins its properties.
Figure. Photoluminescence spectrum of the 532 centre under 473 nm excitation at 300 K.