93 research outputs found
Efficient fabrication of high-density ensembles of color centers via ion implantation on a hot diamond substrate
Nitrogen-Vacancy (NV) centers in diamond are promising systems for quantum
technologies, including quantum metrology and sensing. A promising strategy for
the achievement of high sensitivity to external fields relies on the
exploitation of large ensembles of NV centers, whose fabrication by ion
implantation is upper limited by the amount of radiation damage introduced in
the diamond lattice. In this works we demonstrate an approach to increase the
density of NV centers upon the high-fluence implantation of MeV N2+ ions on a
hot target substrate (>550 {\deg}C). Our results show that, with respect to
room-temperature implantation, the high-temperature process increases the
vacancy density threshold required for the irreversible conversion of diamond
to a graphitic phase, thus enabling to achieve higher density ensembles.
Furthermore, the formation efficiency of color centers was investigated on
diamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions
revealing that the formation efficiency of both NV centers and
magnesium-vacancy (MgV) centers increases with the implantation temperature.Comment: 12 pages, 5 figure
Fabrication of quantum emitters in aluminium nitride by Al-ion implantation and thermal annealing
Single-photon emitters (SPEs) within wide-bandgap materials represent an
appealing platform for the development of single-photon sources operating at
room temperatures. Group III- nitrides have previously been shown to host
efficient SPEs which are attributed to deep energy levels within the large
bandgap of the material, in a way that is similar to extensively investigated
colour centres in diamond. Anti-bunched emission from defect centres within
gallium nitride (GaN) and aluminium nitride (AlN) have been recently
demonstrated. While such emitters are particularly interesting due to the
compatibility of III-nitrides with cleanroom processes, the nature of such
defects and the optimal conditions for forming them are not fully understood.
Here, we investigate Al implantation on a commercial AlN epilayer through
subsequent steps of thermal annealing and confocal microscopy measurements. We
observe a fluence-dependent increase in the density of the emitters, resulting
in creation of ensembles at the maximum implantation fluence. Annealing at 600
{\deg}C results in the optimal yield in SPEs formation at the maximum fluence,
while a significant reduction in SPE density is observed at lower fluences.
These findings suggest that the mechanism of vacancy formation plays a key role
in the creation of the emitters, and open new perspectives in the defect
engineering of SPEs in solid state.Comment: 11 pages, 7 figure
Fabrication of quantum emitters in aluminum nitride by Al-ion implantation and thermal annealing
Single-photon emitters (SPEs) within wide-bandgap materials represent an appealing platform for the development of single-photon sources operating at room temperatures. Group III-nitrides have previously been shown to host efficient SPEs, which are attributed to deep energy levels within the large bandgap of the material, in a configuration that is similar to extensively investigated color centers in diamond. Anti-bunched emission from defect centers within gallium nitride and aluminum nitride (AlN) have been recently demonstrated. While such emitters are particularly interesting due to the compatibility of III-nitrides with cleanroom processes, the nature of such defects and the optimal conditions for forming them are not fully understood. Here, we investigate Al implantation on a commercial AlN epilayer through subsequent steps of thermal annealing and confocal microscopy measurements. We observe a fluence-dependent increase in the density of the emitters, resulting in the creation of ensembles at the maximum implantation fluence. Annealing at 600 °C results in the optimal yield in SPEs formation at the maximum fluence, while a significant reduction in SPE density is observed at lower fluences. These findings suggest that the mechanism of vacancy formation plays a key role in the creation of the emitters and open enticing perspectives in the defect engineering of SPEs in solid state
Cohesive properties of alkali halides
We calculate cohesive properties of LiF, NaF, KF, LiCl, NaCl, and KCl with
ab-initio quantum chemical methods. The coupled-cluster approach is used to
correct the Hartree-Fock crystal results for correlations and to systematically
improve cohesive energies, lattice constants and bulk moduli. After inclusion
of correlations, we recover 95-98 % of the total cohesive energies. The lattice
constants deviate from experiment by at most 1.1 %, bulk moduli by at most 8 %.
We also find good agreement for spectroscopic properties of the corresponding
diatomic molecules.Comment: LaTeX, 10 pages, 1 figure, accepted by Phys. Rev.
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