Enhancement of the creation yield of NV ensembles in a chemically vapour deposited diamond

In this work we investigate the properties of negatively charged nitrogen-vacancy (NV-) centres created during single crystal diamond growth by chemical vapour deposition (CVD) on [113]-oriented substrates and with N2O as a dopant gas. The use of spin echo and double electron-electron resonance (DEER) allows us to assess NV- ratio with respect to substitutional nitrogen impurities (N-s(0)) incorporated during growth, a critical figure of merit for quantum technologies. We demonstrate that, at moderate growth temperatures (800 degrees C), dense NV- ensembles of several hundreds of ppb (800 ppb for 50 ppm of added N2O) and with exceptionally high NV-/ N0s ratios of up to 25% can be achieved. This NV- creation yield is higher by at least an order of magnitude to that typically obtained on standard [100]-grown diamonds and comparable to the best values reported for electron-irradiated diamonds. The material obtained here thus advantageously combines a high NV- density, high creation yield, long coherence times of several tens of ms together with a partial preferential orientation. These are highly desirable requirements for diamond-based quantum sensors that may spur new developments with this crystalline orientation leading to improved performance and sensitivity.(c) 2022 Elsevier Ltd. All rights reserved.