Advanced Applications of Diamond NV Color Centers – ADVICE

Task 1 is devoted to the CVD growth of diamond films with engineered properties, following several approaches:
- Ultrapure single-crystal diamond layers will be grown and will serve as the basic material to host the implanted NV centres.
- Diamond films with a highly nitrogen-doped buried layer will be prepared in order to optimize the two complementary parameters relevant for the magnetometer sensitivity : concentration of NV defects and spin dephasing T2-time.
- Epitaxial growth of a highly pure CVD layer will also be carried out on an implanted sample so that the produced NV centres are away from the surface and its detrimental influence on T2-time.
- Diamond films embedding a moderate amount of nitrogen impurities (in the ppm range) will be grown, in order to activate NV defects with a high conversion yield.
Task 2 uses ion implantation through nanochannels in order to build an array of NV centers with controlled nanometer position. The figure-of-merit of the implantation is given by:
- The conversion yield between implanted nitrogen and converted NV defects ;
- The spatial resolution in the implantation process will be evaluated using super-resolution optical microscopy ;
- The spin coherence time of the implanted NV defects.
Task 3 will develop a wide-field magnetic imaging device based on the spin response of an ensemble of NV defects. Its sensitivity will be evaluated with respect to the shotnoise limit.
Finally, Task 4 will explore different methods to realize diamond nanowires or AFM tips hosting NV defects, and study the resulting luminescent properties. Diamond nanostructures can be achieved by top-down and bottom-up approaches. Combined lithography and dry etching will result in diamond nanowires or tips, with embedded or post-implanted NV defects. We will investigate an alternative approach consiting in the direct growth of a diamond structure in a silicon mould from diamond nanocrystals, with embedded or post implanted NV defects.

1. CVD-growth of ultrapure diamond layers with very low surface rugosity, suited for ion implantation or for cutting polished blade self-supporting layers.

2. Development of homoepitaxial growth techniques allowing us to control the creation of NV centers: Spatial localization in depth and preferred orientation of the NV axis which is controlled by the crystalline orientation of the growth substrate.

3. Manufacturing of single-crystal diamond tips embedding a single NV center, then achieving a record of the luminescence collection efficiency of this emitter. The parameters are the spin electronic state (linewidth of the ESR line) are comparable to those in bulk diamaond, which will lead to a strong sensitivity enhancement compared to functionalized tips with a nanodiamond attached at the apex.

4. Engineering of NV defects using FIB technology based on an ion beam extracted from a nitrogen «Electron Cyclotron Resonance« gas source. This result has lead to a new ANR project in the 2013 P2N program between LAC and the French company ORSAY PHYSICS. The project will allow us to build an optimized FIB machine dedicated to ion implantation. The objective will be to achieve a resolution exceeding 10 nm for the creation of NV centers with the opportunity to simultaneously image the implanted area by dual electron microscopy.

5. Realization of an «wide-field« imaging device based on a shallow implanted NV layer. The magnetic resonance of the NV ensemble recorded in each pixels allowed us to reconstruct the vectorial magnetic field distribution with the standard resolution of confocal optical microscopy. This result has far-reaching applications since there is no equivalent technique for recording such information with a quantitative measurement of the magnetic field amplitude.

The perpectives of ADVICE are:

1. The «wide-field« magnetic imager will allow us to record two-dimensional magnetic structures in a routine way. The system can be improved in order o provide a temporal resolution of the magnetic field, as required for the understanding of spectific structures in spintronics.

2. The realization of single-crystal diamond AFM tips embedding a NV center with a controlled orientation that optimizes the luminescence collection efficiency is a key result for the development of scanning magnetic microscopy based on the ESR of a single NV center. This technique has currently no equivalent for studying and understanding the structure of complex magnetic fields at the nanoscale.

3. We proposed a scheme for measuring a magnetic field with a sensitivity at the pT level. The configuration is based on the intra-cavity absorption of a probe beam at 1042-nm wavelength, tuned to the infrared transition between the singlet states of the NV center. This scheme is well suited to the production of highly sensitive magnetometers, compact and robust. Potential applications are the detection of magnetic anomalies used for instance in geodesy and oil exploration.

4. The project has demonstrated two complementary techniques for the implantation of NV centers with a potential resolution in the 10-nm range. The first technique is based on a mask which has previously been deposited at the surface of the sample and then etched to engineer implantation channels. The second technique is based on a FIB column based on a nitrogen gas source. The ion beam hits a collimating aperture which can raster scanned over the sample. Potential applications of these techniques are related to quantum information. These are long-term goals, but which might be crucial for the realization of quantum simulators or cryptographic tasks.

Publications (July 2014) :

1. J.-P. Tetienne, L. Rondin, P. Spinicelli, M. Chipaux,
T. Debuisschert, J.-F. Roch, and V. Jacques, “Magnetic field- dependent photodynamics of single NV defects in diamond : an application to qualitative all-optical magnetic imaging”,
New J. Phys. 14, 103033 (2012) - arXiv:1206 .1201

2. Y. Dumeige, M. Chipaux, V. Jacques, F.Treussart, J.-F. Roch,
T. Debuisschert, V. M. Acosta, A. Jarmola, K. Jensen, P. Kehayias, and D. Budker, “Magnetometry with nitrogen-vacancy ensembles in diamond based on infrared absorption in a doubly resonant optical cavity”,
Phys. Rev. B 87, 155202, (2013) – arXiv:1301.0808

3. M. Lesik, P. Spinicelli, S. Pezzagna, P. Happel, V. Jacques,
O. Salord, B. Rasser, A. Delobbe, P. Sudraud, A. Tallaire,
J. Meijer, and J.-F. Roch, “Maskless and targeted creation of arrays of colour centres in diamond using focused ion beam technology”,
Phys. Stat. Sol. A 210, 2055-2059 (2013) – arXiv:1304.6619

4. M. Lesik, J.-P. Tetienne, A. Tallaire, J. Achard, V. Mille, A. Gicquel, J.-F. Roch, and V. Jacques, “Perfect preferential orientation of nitrogen-vacancy defects in a synthetic diamond sample”,
Appl. Phys.Lett. 104, 113107 (2014) – arXiv:1401.2795

We submitted a proposal for a European integrated project under the FP7 ICT call-2013-10: FET Proactive: «Atomic and Molecular Scale Devices and Systems«. The project, which acronym is DIADEMS is focused on the applications of NV centers for magnetic sensing. The proposal was ranked first in the evaluation process. It is coordinated by THALES. The ADVICE ANR project was the basis for the constitution of the DIADEMS consortium which gathers the main European players in the field, gathering 15 partners among them THALES, LAC and LSPM at French level. The project started on 1 September 2013 for a period of 4 years.

The main objective of the project ADVICE (ADVanced applications of dIamond NV color CEnters) is to develop innovative devices with unprecedented performances based on the unique physical properties of NV color centers in ultrapure single-crystal CVD-grown diamond. There are three main goals. First, we will deterministically implant single NV defects with 10-nm spatial resolution to develop a scalable spin array aimed to processing of quantum information. Second, we will engineer ensembles of NV color centers with long coherence time and we will use their electron spin resonance for high sensitivity magnetometry. Third, we will engineer high purity CVD-grown diamond crystals hosting controlled amount of NV color centers to produce all-diamond AFM tips and micropillars for applications in tip-based magnetometry and for the realization of efficient single-photon sources.

The project gathers two academics partners (LPQM / CNRS and ENS Cachan ; LSPM / CNRS and Université Paris-XIII) and two industrial partners (Thales Research and Technology: TRT ; CEA LIST). In addition a German partner (Ruhr Universität: Rubion) will participate without being subsidized. All together, the partners master the complete chain from NV defects engineering in ultrapure CVD diamond using ion implantation to the use of these devices in magnetometry and quantum information processing.

LQPM will coordinate the project. From the scientific point of view, LPQM will be the task leader in charge of the high sensitivity magnetometer set-up. In addition, it will be involved in other tasks of the project such as the implantation of single NV defects and their characterization using STED microscopy. LSPM will be the task leader in charge of the CVD synthesis of single-crystal diamonds with controlled properties, providing samples to the other partners for their own task. In addition, LSPM will test original CVD growth techniques in order to achieve high density of NV centers with long spin coherence time. Thales will be the task leader in charge of the deterministic implantation of single NV defects, in particular through the realization of masks using electron-beam lithography. Thales will also actively contribute to the development of the high sensitivity magnetometer. CEA LIST will be the task leader for diamond nanostructure engineering and the control of surface effects. Rubion is the specialist of nitrogen ion implantation in diamond, which is the technique that will be used to engineer the NV defects inside high-purity diamond slabs.

ADVICE is a basic research project oriented towards applications. The unique coherence properties of NV centers, still existing at room temperature, are very promising for solid-state coherent sensors. The tasks pursued in the project can directly lead to exploitable results concerning the partners developing industrial applications: Thales and CEA. Possible applications are : high sensitivity magnetometer for magnetic anomaly detectors, wide-field magnetic imaging systems useful for spintronics or for ion exchange monitoring in living cell, Silicon-On-Diamond technology allowing to relax the heating problems faced in modern microprocessors, and surface wave filters on diamond substrates with unprecedented quality and bandwidth.

The results obtained by the members of the consortium will be reported in peer-reviewed journals and conferences. A particular attention will be paid to their protection. No publication will be made without agreement of all partners and prior search for patentability as it will be stated in the consortium agreement.

As a conclusion, the success of ADVICE will imply a major step in the comprehension and control of the basic properties of NV color centers in ultrapure diamond as well as in the development of their far-reaching potential applications. The project is therefore a strategic investment in one very promising field of present technology.