Non-radiative processes in deep centres of diamond

John Wickham Steeds, Hmb Darwish, Joseph M. Hayes

Victor S. Vavilov, A. A. Gippius, E.A. Konorova

Lachlan J. Rogers

Infrared emission has been observed for the nitrogen-vacancy (NV −) colour centre in diamond, in addition to the characteristic red emission of this centre [1]. However, this infrared emission zero-phonon line at 1046 nm is about four orders of magnitude weaker than the red emission. This is somewhat surprising, as a third of the population is known to decay without the red emission and the infrared emission is considered to be associated with the alternative decay path. The most obvious explanation is a competing effcient non-radiative decay. There are few reports of diamond emitting at wavelengths longer than 1000 nm. Colour centres in diamond have strong electron-phonon coupling and, of course, the phonon energies in diamond are high. These properties suggest that non-radiative decay could dominate the transition whenever the electronic energy lies in the infrared. This would be a general phenomena and would account for the weak IR emission observed for this centre. It would also account for why there are so few reports of emission from diamond in the infrared.

De Sa

Margarita Lesik, Nicole Raatz, Alexandre Tallaire +8 more

The nanometer‐scale engineering of single nitrogen‐vacancy (NV) centres in diamond can be obtained by low‐energy (keV) nitrogen implantation with limited straggling. However, shallow NV centres (a few nanometres deep) generally have inferior overall properties than deeply implanted or deep native NV centres, due to the surface proximity. It has already been shown that the spin coherence time of shallow NVs is improved by overgrowth of a thin diamond layer. However the influence of the overgrowth on the survival, the optical properties and the charge state of the centres has not been studied in detail. In this article, we have overgrown three diamond samples (containing NV centres implanted at different depths) using different procedures. We show the successful overgrowth of a pattern of very shallow (2 nm) implanted NV centres using an optimised overgrowth process. Furthermore, the charge state of ensembles and single NV centres was found to be shifted from NV0 to NV− and stabilised in the negative charge state after overgrowth. The combination of low‐energy high‐resolution ion implantation and high‐purity chemical vapour deposition (CVD) overgrowth procedures opens the way towards the fabrication of scalable and efficient quantum devices based on single defects in diamond. Left: implanted pattern of very shallow NV centres (depth ∼2 nm) using a pierced AFM tip. Right: same pattern after CVD overgrowth of a 4 μm‐thick diamond layer.

Andreas Angerer, Kirill Streltsov, Thomas Astner +8 more