242 research outputs found
Magnetic imaging with an ensemble of Nitrogen Vacancy centers in diamond
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 exploit the ODMR signal of an ensemble of NV
centers in order to quantitatively map the vectorial structure of a magnetic
field produced by a sample close to the surface of a CVD diamond hosting a thin
layer of NV centers. The reconstruction of the magnetic field 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 {\mu}m^2 area of the doped layer, equivalent to a sensor
consisting of approximately 10^4 NV centers, is of the order of 2
{\mu}T/sqrt{Hz}. The spatial resolution of the imaging device is 400 nm,
limited by the numerical aperture of the optical microscope which is used to
collect the photoluminescence of the NV layer. The versatility of the sensor is
illustrated by the accurate reconstruction of the magnetic field created by a
DC current inside a copper wire deposited on the diamond sample.Comment: 11 pages, 5 figures, figure 4 added, results unchange
Perfect preferential orientation of nitrogen-vacancy defects in a synthetic diamond sample
We show that the orientation of nitrogen-vacancy (NV) defects in diamond can
be efficiently controlled through chemical vapor deposition (CVD) growth on a
(111)-oriented diamond substrate. More precisely, we demonstrate that
spontaneously generated NV defects are oriented with a ~ 97 % probability along
the [111] axis, corresponding to the most appealing orientation among the four
possible crystallographic axes. Such a nearly perfect preferential orientation
is explained by analyzing the diamond growth mechanism on a (111)-oriented
substrate and could be extended to other types of defects. This work is a
significant step towards the design of optimized diamond samples for quantum
information and sensing applications.Comment: 6 pages, 4 figure
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 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
Optical Detection of Paramagnetic Defects in a CVD-grown Diamond
The electronic spins of the nitrogen-vacancy centers (NV centers) in
Chemical-Vapor-Deposition (CVD) grown diamonds form ideal probes of magnetic
fields and temperature, as well as promising qu-bits for quantum information
processing. Studying and controlling the magnetic environment of NV centers in
such high purity crystals is thus essential for these applications. We
demonstrate optical detection of paramagnetic species, such as hydrogen-related
complexes, in a CVD-grown diamond. The resonant transfer of the NV centers'
polarized electronic spins to the electronic spins of these species generates
conspicuous features in the NV photoluminescence by employing magnetic field
scans along the [100] crystal direction. Our results offer prospects for more
detailed studies of CVD-grown processes as well as for coherent control of the
spin of novel classes of hyper-polarized paramagnetic species.Comment: 8 pages including appendi
Tribological testing of self-mated nanocrystalline diamond coatings on Si3N 4 ceramics
Due to their much lower surface roughness compared to that of microcrystalline diamond, nanocrystalline diamond (NCD) films are promising candidates for tribological applications in particular when deposited on hard ceramic materials such as silicon nitride (Si3N4). In the present work, microwave plasma assisted chemical vapour deposition of NCD is achieved using Ar/H2/CH4 gas mixtures on plates and ball-shaped Si3N4 specimens either by a conventional continuous mode or a recently developed pulsed regime. The microstructure, morphology, topography and purity of the deposited films show typical NCD features for the two kinds of substrate shapes. Besides, tribological characterisation of the NCD/Si3N4 samples is carried out using self-mated pairs without lubrication in order to assess their friction and wear response. Worn surfaces were studied by SEM and AFM topography measurements in order to identify the prevalent wear mechanisms. Friction values reached a steady-state minimum of approximately 0.03 following a short running-in period where the main feature is a sharp peak which attained a maximum around 0.45. Up to the critical load of 35 N, corresponding to film delamination, the equilibrium friction values are similar, irrespective of the applied load. The calculated wear coefficient values denoted a very mild regime (K ~ 1x10-8 mm3N-1m-1) for the self-mated NCD coatings. The predominant wear mechanism was identified as self-polishing by micro-abrasion
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