Enhanced surface transfer doping of diamond by V2O5 with improved thermal stability

Surface transfer doping of hydrogen-terminated diamond has been achieved utilising V2O5 as a surface electron accepting material. Contact between the oxide and diamondsurface promotes the transfer of electrons from the diamond into the V2O5 as revealed by the synchrotron-based high resolution photoemission spectroscopy. Electrical characterization by Hall measurement performed before and after V2O5 deposition shows an increase in hole carrier concentration in the diamond from 3.0 × 1012 to 1.8 × 1013 cm−2 at room temperature. High temperature Hall measurements performed up to 300 °C in atmosphere reveal greatly enhanced thermal stability of the hole channel produced using V2O5 in comparison with an air-induced surface conduction channel. Transfer doping of hydrogen-terminated diamond using high electron affinity oxides such as V2O5 is a promising approach for achieving thermally stable, high performance diamond based devices in comparison with air-induced surface transfer dopin

Photonic nano-structures on (111) oriented diamond

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 10${}^6$ 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.Comment: 4 pages original manuscript, 3 pages supplementary materia

Ultrathin Eu- and Er-Doped Y2O3 Films with Optimized Optical Properties for Quantum Technologies

Atomic layer deposited (ALD) YO thin films have been thoroughly investigated for optical or electronic applications. The coherent spectroscopy of lanthanide ions doped into this material has also recently attracted increasing interest in the field of quantum technologies for which they are considered promising candidates in quantum memories or as spin-photon interfaces. However, these most demanding applications require a deep control over the local positioning of the ions and their close environment in the crystalline matrix. This study focuses on the structural as well as optical properties of Eu and Er dopants in YO using photoluminescence (PL), luminescence decay times, and inhomogeneous line width (Γ) measurements within this particular context. While as-grown ALD films do not provide an ideal host for the emitters, we demonstrate that by optimizing the deposition conditions and using appropriate annealing post treatments narrow inhomogeneous lines can be obtained for the F↔D transition of Eu even for nanoscale films. Furthermore, about 1.5 ms lifetime has been measured for the infrared telecom transition of Er in ultrathin films (<10 nm), which is an order of magnitude higher than in nanoparticles of the same size. These results validate optimized rare-earth-doped ALD YO films as a suitable platform for photonics applications where few-nanometer-thick films with well-localized emitters are mandatory. This approach provides the first building blocks toward the development of more complex devices for quantum sensing or hybrid structures coupled with other systems such as two-dimensional materials

Fast electrical modulation of strong near-field interactions between erbium emitters and graphene

Combining the quantum optical properties of single-photon emitters with the strong near-field interactions available in nanophotonic and plasmonic systems is a powerful way of creating quantum manipulation and metrological functionalities. The ability to actively and dynamically modulate emitter-environment interactions is of particular interest in this regard. While thermal, mechanical and optical modulation have been demonstrated, electrical modulation has remained an outstanding challenge. Here we realize fast, all-electrical modulation of the near-field interactions between a nanolayer of erbium emitters and graphene, by in-situ tuning the Fermi energy of graphene. We demonstrate strong interactions with a >1000-fold increased decay rate for ~25% of the emitters, and electrically modulate these interactions with frequencies up to 300 kHz - orders of magnitude faster than the emitter's radiative decay (~100 Hz). This constitutes an enabling platform for integrated quantum technologies, opening routes to quantum entanglement generation by collective plasmon emission or photon emission with controlled waveform

Screening and engineering of colour centres in diamond

We present a high throughput and systematic method for the screening of colour centres in diamond with the aim of searching for and reproducibly creating new optical centres down to the single defect level, potentially of interest for a wide range of diamond-based quantum applications. The screening method presented here should, moreover, help to identify some already indexed defects among hundreds in diamond (Zaitsev 2001 Optical Properties of Diamond (Berlin: Springer)) but also some promising defects of a still unknown nature, such as the recently discovered ST1 centre (Lee et al 2013 Nat. Nanotechnol. 8 487; John et al 2017 New J. Phys. 19 053008). We use ion implantation in a systematic manner to implant several chemical elements. Ion implantation has the advantage of addressing single atoms inside the bulk with defined depth and high lateral resolution, but the disadvantage of producing intrinsic defects. The implanted samples are annealed in vacuum at different temperatures (between 600 degrees C and 1600 degrees C with 200 degrees C steps) and fully characterised at each step in order to follow the evolution of the defects: formation, dissociation, diffusion, re-formation and charge state, at the ensemble level and, if possible, at the single centre level. We review the unavoidable ion implantation defects (such as the GR1 and 3H centres), discuss ion channeling and thermal annealing and estimate the diffusion of the vacancies, nitrogen and hydrogen. We use different characterisation methods best suited for our study (from widefield fluorescence down to subdiffraction optical imaging of single centres) and discuss reproducibility issues due to diamond and defect inhomogeneities. Nitrogen is also implanted for reference, taking advantage of the considerable 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.Peer reviewe

Optical coherence properties of Kramers' rare-earth ions at the nanoscale for quantum applications

Rare-earth (RE) ion doped nano-materials are promising candidates for a range of quantum technology applications. Among RE ions, the so-called Kramers' ions possess spin transitions in the GHz range at low magnetic fields, which allows for high-bandwidth multimode quantum storage, fast qubit operations as well as interfacing with superconducting circuits. They also present relevant optical transitions in the infrared. In particular, Er$^{3+}$ has an optical transition in the telecom band, while Nd$^{3+}$ presents a high-emission-rate transition close to 890 nm. In this paper, we measure spectroscopic properties that are of relevance to using these materials in quantum technology applications. We find the inhomogeneous linewidth to be 10.7 GHz for Er$^{3+}$ and 8.2 GHz for Nd$^{3+}$, and the excited state lifetime T$_1$ to be 13.68 ms for Er$^{3+}$ and 540 $\mu$s for Nd$^{3+}$. We study the dependence of homogeneous linewidth on temperature for both samples, with the narrowest linewidth being 379 kHz (T$_2$ = 839 ns) for Er$^{3+}$ measured at 3 K, and 62 kHz (T$_2$ = 5.14 $\mu$s) for Nd$^{3+}$ measured at 1.6 K. Further, we investigate time-dependent homogeneous linewidth broadening due to spectral diffusion and the dependence of homogeneous linewidth on magnetic field, in order to get additional clarity of mechanisms that can influence the coherence time. In light of our results, we discuss two applications: single qubit-state readout and a Fourier-limited single photon source.Comment: 9 pages, 5 figure

Ingénierie des défauts multidimensionnels dans le diamant synthétisé par dépôt chimique en phase vapeur assisté par plasma

Outre le fait qu’il soit une pierre gemme suscitant une grande convoitise, le diamant est un matériau présentant un très fort potentiel technologique du fait de ses propriétés mécaniques, thermiques ou électroniques extrêmes. Au cours des 2 dernières décennies, des progrès significatifs ont été acquis dans la synthèse de monocristaux millimétriques par la technique du dépôt chimique en phase vapeur assisté par plasma micro-onde (MPACVD). A l’heure actuelle la pureté des cristaux CVD dépasse de loin celle des meilleurs diamants naturels disponibles ce qui ouvre de fantastiques perspectives d’exploitation industrielles de ce matériau. En parallèle le niveau d’exigence en termes de quantité de défauts ponctuels et étendus contenus dans ces cristaux est devenu très élevé et nécessite des efforts importants d’optimisation de la méthode de synthèse. Dans ce manuscrit présenté en vue d’obtenir l’HDR j’ai cherché à réaliser un bilan de mes activités menées au LSPM et concernant l’étude et la maitrise des défauts cristallins dans le diamant CVD. Après une introduction générale permettant de positionner ce matériau sur le plan industriel, une hiérarchie dimensionnelle a été choisie pour l’organisation du manuscrit. Ainsi la croissance de monocristaux épais dénués de macles ou cristallites non-épitaxiales (défauts larges 3D) est décrite, principalement sur des substrats conventionnels orientés (100) puis sur des orientations moins classiques telles que (111) et (113). Je me suis également fortement intéressé aux dislocations (défauts étendus 1D). Après avoir assuré leur identification et dénombrement dans les cristaux CVD, des stratégies originales ont ainsi été mises en œuvre pour tenter de réduire leur apparition, en les bloquant ou déviant lors de la croissance. Finalement les impuretés et lacunes (défauts ponctuels 0D) représentent un enjeu important car même en très faible quantité elles conditionnent beaucoup les propriétés d’usage finales du diamant. Ainsi la création contrôlée et la localisation spatiale des centres luminescents tels que les complexes azote-lacune (dits centres NV) a été menée en raison du fort intérêt qu’ils suscitent pour l’information quantique et la réalisation de détecteurs ultra-sensibles

Growth of thick CVD diamond films on different crystalline orientations

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