Engineering Color Centers in Isotopically-Controlled Diamond Layers

Nitrogen-vacancy (NV) centers in synthetic tailored diamond are promising and emerging platforms for quantum sensing technologies. The realization of such solid-state based quantum sensors is widely studied and requires reproducible manufacturing of NV centers with controlled spin properties, including the spin bath environment within the diamond crystal. A high nitrogen incorporation rate combined with the controllability of the NV axis alignment, makes &lt;111&gt; oriented diamond an interesting material for the creation of ensembles.<br/>We engineer ¹⁵NVs by nitrogen delta doping during a plasma enhanced chemical vapor deposition (PECVD) process and we are able to produce an isotopically controlled diamond environment by changing the ratio of ¹²C/¹³C atoms in the growth chamber. Moreover, since the presence of ¹⁵NV hyperfine coupling, as well as the characteristic P1 bath spectrum from ¹⁵N are observed, our growth facilities are capable of tuning a wide range of isotopic compounds within the diamond lattice.<br/>Especially, shallow ensembles can be used for NV based magnetometry optimized for the detection of very small magnetic fields from outside of the diamond itself. Whereby the decoupling of the NV's electronic spins by driving the electronic spin bath and by using dynamical decoupling sequences results in an improved magnetic field sensitivity.<br/><br/>In summary, a non-invasive method is shown to rank NV ensembles regarding their suitability as ultra-sensitive magnetic field sensors. Imaging and electron spin resonance techniques are presented to determine operating figures and precisely define the optimal material for NV-driven diamond engineering. The functionality of the methods is manifested on examples of chemical vapor deposition synthesized diamond layers containing preferentially-aligned, isotopically controlled ¹⁵NV center ensembles. Quantification of the limiting ¹⁵N P1 spin bath, in an otherwise ¹²C enriched environment, and the reduction of its influence by applying dynamical decoupling protocols, complete the suggested set of criteria for the analysis of NV ensemble with potential use as magnetometers.<br/><br/>References:<br/>Osterkamp et al. (2020), Adv. Quantum Technol., 3: 2000074