Enhanced magnetic field sensitivity of shallow NV− ensembles via high-temperature implantation
J. Al Yahya, A. Bach, J. Panigrahi, P. Perrin, Ionuț Gabriel Balașa, Diana Serrano, Alexey Tiranov, Jocelyn Achard, Alexandre Tallaire, Philippe Goldner
Dense and shallow ensembles of negatively charged nitrogen-vacancy center (NV−) with good optical and spin properties play a key role in the performance enhancement of diamond-based quantum sensors. Ion implantation enables precise control of NV− depth and density. However, at high ion fluence, this method is limited by low NV− creation yields and sample amorphization. Additionally, shallow NV− spin properties deteriorate due to surface proximity. In this paper, we study N2+ ion implantation at energies between 10 and 15 keV with fluences as high as 1×1015 ions/cm2 at temperatures of 20, 400, and 800°C to investigate the influence of implantation temperature on lattice damage, NV− creation yield, and NV− spin properties. Our results show that diamond maintains structural integrity at 800°C with fluences up to 1×1015 ions/cm2 without amorphization. Furthermore, high-temperature implantation improves NV− creation yields up to five times without compromising T2∗, T2, and T1, making it a promising approach to enhance the magnetic field sensitivity of NV− ensembles.
Dense and shallow ensembles of negatively charged nitrogen-vacancy center (NV−) with good optical and spin properties play a key role in the performance enhancement of diamond-based quantum sensors. Ion implantation enables precise control of NV− depth and density. However, at high ion fluence, this method is limited by low NV− creation yields and sample amorphization. Additionally, shallow NV− spin properties deteriorate due to surface proximity. In this paper, we study N2+ ion implantation at energies between 10 and 15 keV with fluences as high as 1×1015 ions/cm2 at temperatures of 20, 400, and 800°C to investigate the influence of implantation temperature on lattice damage, NV− creation yield, and NV− spin properties. Our results show that diamond maintains structural integrity at 800°C with fluences up to 1×1015 ions/cm2 without amorphization. Furthermore, high-temperature implantation improves NV− creation yields up to five times without compromising T2∗, T2, and T1, making it a promising approach to enhance the magnetic field sensitivity of NV− ensembles.
Enhanced magnetic field sensitivity of shallow NV− ensembles via high-temperature implantation
Dense and shallow ensembles of negatively charged nitrogen-vacancy centers (NV−) with good optical and spin properties play a key role in the performance enhancement of diamond-based quantum sensors. Ion implantation enables precise control of NV− depth and density. However, at high ion fluence, this method is limited by low NV− creation yields and sample amorphization. Additionally, shallow NV− spin properties deteriorate due to surface proximity. In this paper, we study N2+ ion implantation at energies between 10 and 15 keV with fluences as high as 1e15 ions/cm2 at temperatures of 20, 400 and 800°C to investigate the influence of implantation temperature on lattice damage, NV− creation yield and NV− spin properties. Our results show that diamond maintains structural integrity at 800°C with fluences up to 1e15 ions/cm2 without amorphization. Furthermore, high-temperature implantation improves NV− creation yields up to five times without compromising T2∗, T2 and T1, making it a promising approach to enhance the magnetic field sensitivity of NV− ensembles.
Creating dense and shallow nitrogen-vacancy (NV) ensembles with good spin properties is a prerequisite for developing diamond-based quantum sensors exhibiting better performance. Ion implantation is a key enabling tool for precisely controlling spatial localization and density of NV color centers in diamond. However, it suffers from a low creation yield, while higher ion fluences significantly damage the crystal lattice. In this work, we realize N2+ ion implantation in the 30–40 keV range at high temperatures. At 800 °C, NV's ensemble photoluminescence emission is three to four times higher than room temperature implanted films, while narrow electron spin resonance linewidths of 1.5 MHz, comparable to well-established implantation techniques, are obtained. In addition, we found that ion fluences above 2 × 1014 ions/cm2 can be used without graphitization of the diamond film, in contrast to room temperature implantation. This study opens promising perspectives in optimizing diamond films with implanted NV ensembles that could be integrated into quantum sensing devices.
Creating dense and shallow nitrogen vacancy (NV) ensembles with good spin properties, is a prerequisite for developing diamond-based quantum sensors exhibiting better performance. Ion implantation is a key enabling tool for precisely controlling spatial localisation and density of NV colour centres in diamond. However, it suffers from a low creation yield, while higher ion fluences significantly damage the crystal lattice. In this work, we realize N2 ion implantation in the 30 to 40 keV range at high temperatures. At 800 C, NV ensemble photoluminescence emission is three to four times higher than room temperature implanted films, while narrow electron spin resonance linewidths of 1.5 MHz, comparable to well established implantation techniques are obtained. In addition, we found that ion fluences above 2E14 ions per cm2 can be used without graphitization of the diamond film, in contrast to room temperature implantation. This study opens promising perspectives in optimizing diamond films with implanted NV ensembles that could be integrated into quantum sensing devices.
Efficient creation of shallow NV− ensembles by high-angle ion implantation
Negatively charged nitrogen-vacancy (NV−) centers located a few nanometers below the diamond surface are key quantum defects for nanoscale sensing of external spins. However, the creation of shallow NV− centers with high yield remains a materials challenge. Here, we demonstrate that high-angle ion implantation enhances the creation efficiency of shallow NV− centers. By implanting 15N ions at angles exceeding 60∘, we achieve high NV− yields approaching 10% with effective NV− depths below 10 nm. These yields are significantly higher than those typically reported for shallow NV− creation. The enhanced NV− yield is consistent with an increased vacancy-to-nitrogen ratio in the near-surface region, which is expected to promote NV formation during annealing. The created NV− ensembles show coherence properties comparable to those of single shallow NV− centers at similar depths, and allow detection of nuclear spins in van der Waals materials attached to the diamond surface. Our results establish geometric control of ion implantation as a simple and broadly applicable approach to engineer shallow vacancy-related quantum defects.
Abstract The negatively charged nitrogen-vacancy centre (so-called NV-centre) in diamond is one of the most promising systems for applications in quantum technologies because of the possibility to optically manipulate and read out the spin state of this defect, even at room temperature. Nevertheless, obtaining high NV densities (>500 ppb) close to the surface (5–20 nm) while maintaining good spin properties remain challenging. In this work we rely on a versatile ion implantation system allowing both implanting nitrogen using N 2 + and creating vacancies with He + ion bombardment at variable energies and fluence to create shallow NV ensembles. By optimizing the ion irradiation conditions as well as the surface preparation prior to treatment we successfully increase the amount of created colour centres while demonstrating narrow magnetic resonance linewidths.
Since nitrogen-vacancy (NV) centers in diamond have emerged as crucial quantum sensors in physics and biology, the massive preparation of high-quality and high-concentration shallow NV center samples has become urgent and demanding. As NV centers approach the surface and their concentration increases, charge state instability can degrade coherence and introduce additional noise. This problem is further complicated in high-pressure and high-temperature (HPHT) diamonds due to the presence of unclear impurities and inhomogeneous strain. Through optically detected magnetic resonance testing on various implanted samples, we analyzed the spin and charge state properties of shallow NV center ensembles. Our results reveal that the doping dose significantly influences the quantity of NV−, charge, and charge stability. Our findings indicate that over-implanting nitrogen as electron donors before starting graphitization helps stabilize the charge environment of the shallow NV center ensembles. By controlling the nitrogen ion implantation dose, we optimized charge state stability under photoionization and prepared high-quality NV center ensemble samples in HPHT diamonds at the optimal implantation dose range of 2×1013–8×1013 ions/cm2. This method, which relies solely on nitrogen ion implantation and annealing on HPHT diamond, significantly reduces the cost of sensor samples, greatly benefiting the promotion of quantum sensing.