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Articles you may be interested inPerfect alignment and preferential orientation of nitrogen-vacancy centers during chemical vapor deposition diamond growth on (111) surfaces Appl. Phys. Lett.

We present a high throughput and systematic method for screening of colour centres in diamond. We aim at the search and reproducible creation of new optical centres, down to the single level, potentially of interest for the wide range of diamond-based quantum applications. The screening method presented here should moreover help identifying some already indexed defects among hundreds in diamond [1] but also some promising defects of still unknown nature, such as the recently discovered ST1 centre [2,3]. We use ion implantation in a systematic manner to implant several chemical elements. Ion implantation has the advantage to address single atoms inside the bulk with defined depth and high lateral resolution, but the disadvantage of defect production such as vacancies. The sample is annealed in vacuum at different temperatures (between 600°C and 1600°C with 200°C steps) and fully characterised at each step in order to follow the evolution of the defects: formation, dissociation, diffusion, reformation and charge state, at the ensemble level and, if possible, at the single centre level. We review the unavoidable ion implantation defects (with the example of the GR1 and 3H centres), discuss ion channeling and thermal annealing and estimate the diffusion of vacancies, nitrogen and hydrogen. We use different characterisation methods best suited for our study (from widefield fluorescence down to sub-diffraction optical imaging of single centres) and discuss reproducibility issues due to diamond and defect inhomogeneities. Nitrogen is also implanted as a reference, taking advantage of the large knowledge on NV centres as a versatile sensor in order to retrieve or deduce the conditions and local environment in which the different implanted chemical elements are embedded. We show here the preliminary promising results of a long-term study and focus on the elements O, Mg, Ca, F and P, from which fluorescent centres were found.

We demonstrate the fabrication of single-crystalline diamond nanopillars on a (111)-oriented chemical vapor deposited diamond substrate. This crystal orientation offers optimal coupling of nitrogen-vacancy (NV) center emission to the nanopillar mode and is thus advantageous over previous approaches. We characterize single native NV centers in these nanopillars and find one of the highest reported saturated fluorescence count rates in single crystalline diamond in excess of 106 counts per second. We show that our nano-fabrication procedure conserves the preferential alignment as well as the spin coherence of the NVs in our structures. Our results will enable a new generation of highly sensitive probes for NV magnetometry and pave the way toward photonic crystals with optimal orientation of the NV center's emission dipole.

The growth of monocrystalline diamond films of electronic quality and large thickness (>few hundreds of microns) is an important issue in particular for high-power electronics. In this paper, we will describe the different key parameters necessary to reach this objective. First, we will examine the deposition process and establish that only microwave assisted diamond deposition plasma reactors can achieve the optimal growth conditions for the efficient generation of the precursor species to diamond growth. Next, we will consider the influence of the monocrystalline diamond substrate orientation and quality on the growth of the epitaxial layer, especially when the deposited material thickness exceeds 100 µm. The need to use a specific pre-treatment procedure of the substrate before the growth and its impact will also be discussed. Finally we will look at the growth conditions themselves and assess the influence of the process parameters, such as the substrate temperature, the methane concentration, the microwave power density and the eventual presence of nitrogen in the gas phase, on both the morphology and quality of the films on the one hand and the growth rate on the other hand. For this, we will introduce the concept of supersaturation and comment on its evolution as a function of the process parameters.

The nitrogen-vacancy (NV) color center in diamond is an atom-like system in the solid-state which specific spin properties can be efficiently used as a sensitive magnetic sensor. An external magnetic field induces Zeeman shifts of the NV center levels which can be measured using Optically Detected Magnetic Resonance (ODMR). In this work, we quantitatively map the vectorial structure of the magnetic field produced by a sample close to the surface of a CVD diamond hosting a thin layer of NV centers. The magnetic field reconstruction is based on a maximum-likelihood technique which exploits the response of the four intrinsic orientations of the NV center inside the diamond lattice. The sensitivity associated to a 1 µm 2 area of the doped layer, equivalent to a sensor consisting of approximately 10 4 NV centers, is of the order of 2 µT/ √ Hz. The spatial resolution of the imaging device is 480 nm, limited by the numerical aperture of the optical microscope which is used to collect the photoluminescence of the NV layer. The effectiveness of the method is illustrated by the accurate reconstruction of the magnetic field created by a DC current inside a copper wire deposited on the diamond sample.

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Devices relying on microwave circuitry form a cornerstone of many classical and emerging quantum technologies. A capability to provide in-situ, noninvasive and direct imaging of the microwave fields above such devices would be a powerful tool for their function and failure analysis. In this work, we build on recent achievements in magnetometry using ensembles of nitrogen vacancy centers in diamond, to present a widefield microwave microscope with few-micron resolution over a millimeterscale field of view, 130 nT Hz −1/2 microwave amplitude sensitivity, a dynamic range of 48 dB, and sub-ms temporal resolution. We use our microscope to image the microwave field a few microns above a range of microwave circuitry components, and to characterize a novel atom chip design. Our results open the way to high-throughput characterization and debugging of complex, multicomponent microwave devices, including real-time exploration of device operation.Microwave (MW) devices play a critical role in telecommunications, defence, and quantum technologies. Device characterization via high resolution MW field imaging is a long-standing goal [1][2][3], which promises to overcome the limitations of conventional characterization techniques. For example, it is difficult to identify internal features of complex devices using S-parameter measurements of reflection and transmission through external device ports [4,5]. A high-throughput MW imaging method would allow for fast prototype iteration, and for more adventurous development of novel device architectures. Furthermore, MW imaging is of interest for spin-wave imaging in magnonic systems [6,7], is under investigation for medical imaging [8,9], and can be used to characterize materials [10] and biological samples [11]. In recent years, alkali vapor cells with atoms in the ground [12][13][14][15][16] or highly excited Rydberg [17][18][19] states, and nitrogen-vacancy (NV) centers in diamond [20-23] have shown promise for intrinsically calibrated MW imaging in simple, vacuum-and cryogen-free environments. Ensembles of NVs in a widefield diamond microscope [24][25][26][27][28] provide an excellent balance between the sensitivity and wide field of view (FOV) offered by vapor cells and the nanoscale spatial resolution of single NV centers [29], and so far have been primarily employed for imaging static and low-frequency magnetic fields. In this work, we demonstrate high-throughput widefield diamond microscopy for MW device characterization, enabled by a step-change we have achieved in microscope performance.Our microscope integrates advances in camera speed, experiment control, novel diamond material, laser illu-