Characterisation of CVD diamond with high concentrations of nitrogen for magnetic-field sensing applications

Abstract

Ensembles of nitrogen-vacancy (NV) centres in diamond are a leading platform for practical quantum sensors. Reproducible and scalable fabrication of NV-ensembles with desired properties is crucial, as is an understanding of how those properties influence performance. This work addresses these issues by characterising nitrogen-doped diamond produced by the chemical vapour deposition (CVD) method across a range of synthesis conditions. This is shown to produce material with widely differing absorption characteristics, which is linked to the level of defects other than substitutional nitrogen (NS) and NV. In such material, the achievable concentration of NV− ([NV−]) is found to be influenced by the as-grown properties. At the 10–20 ppm level for [NS], the production of CVD-grown material with strain levels sufficient not to limit achievable device sensitivity is demonstrated and a favourable product of [NV−] and T 2 * is obtained. Additionally, reproducible properties over a batch of 23 samples from a single synthesis run are achieved, which appears promising for the scalability efforts underway in this area of research.

High NV density in a pink CVD diamond grown with N2O addition

“…It is striking that the T2* values remained roughly the same after irradiation which indicates that one can benefit from the high brightness of a dense NV ensemble without any trade off on the coherence time. Thus the [NV -]×T2* product, indicated by a recent report [29].…”

“…The proportion of neutrally charged nitrogen represents here around 70 % of the total substitutional nitrogen, a fairly high value. According to a recent study [29], it suggests that the amount of acceptor defects was low, a good indicator of the final performance of the material in quantum applications. We note that long-time exposure to UV irradiation of the sample prior to NV -l = 532 nm measurement was not performed although this treatment is known to maximize the proportion of N s 0 respectively to N s + .The value of 70 % might thus be underestimated here.…”

Non-invasive imaging of three-dimensional integrated circuit activity using quantum defects in diamond

“…Over the past decade, many efforts have been deployed to both improve the sensing capabilities of the NV centres [49][50][51][52][53] and to develop techniques to explore new regimes [54][55][56][57]. These combined advances led to remarkable achievements such as revealing electric fields associated with surface band bending in diamond [58] and probing Johnson noise in metals [59].…”

Applicability of gas-jet MPCVD polycrystalline diamond films on silicon with NV centers in quantum magnetometry

“…They are the self-point lattice defect and impurity atom complexes. Due to their long live spin coherence time even at Room Temperatures (RT) they can operate as single photon sources and detectors, quantum memory and registers physical field nanosensors, for example, magnetic, or electric, or stress, or temperature fields with tens nanometer resolution [7][8][9].…”

“…For NV-color center ensembles, the optical shot-noise limited DC magnetic sensitivity (η) R is given by [7]:…”