36 research outputs found
Creation and characterization of He-related color centers in diamond
Diamond is a promising material for the development of emerging applications
in quantum optics, quantum information and quantum sensing. The fabrication and
characterization of novel luminescent defects with suitable opto-physical
properties is therefore of primary importance for further advances in these
research fields. In this work we report on the investigation in the formation
of photoluminescent (PL) defects upon MeV He implantation in diamond. Such
color centers, previously reported only in electroluminescence and
cathodoluminescence regime, exhibited two sharp emission lines at 536.5 nm and
560.5 nm, without significant phonon sidebands. A strong correlation between
the PL intensities of the above-mentioned emission lines and the He
implantation fluence was found in the 10^15-10^17 cm^{-2} fluence range. The PL
emission features were not detected in control samples, i.e. samples that were
either unirradiated or irradiated with different ion species (H, C). Moreover,
the PL emission lines disappeared in samples that were He-implanted above the
graphitization threshold. Therefore, the PL features are attributed to
optically active defects in the diamond matrix associated with He impurities.
The intensity of the 536.5 nm and 560.5 nm emission lines was investigated as a
function of the annealing temperature of the diamond substrate. The emission
was observed upon annealing at temperatures higher than 500{\deg}C, at the
expenses of the concurrently decreasing neutral-vacancy-related GR1 emission
intensity. Therefore, our findings indicate that the luminescence originates
from the formation of a stable lattice defect. Finally, the emission was
investigated under different laser excitations wavelengths (i.e. 532 nm and 405
nm) with the purpose of gaining a preliminary insight about the position of the
related levels in the energy gap of diamond
Development and characterization of a diamond-insulated graphitic multi electrode array realized with ion beam lithography
The detection of quantal exocytic events from neurons and neuroendocrine cells is a challenging task in neuroscience. One of the most promising platforms for the development of a new generation of biosensors is diamond, due to its biocompatibility, transparency and chemical inertness. Moreover, the electrical properties of diamond can be turned from a perfect insulator into a conductive material (resistivity ~mΩ·cm) by exploiting the metastable nature of this allotropic form of carbon. A 16‑channels MEA (Multi Electrode Array) suitable for cell culture growing has been fabricated by means of ion implantation. A focused 1.2 MeV He+ beam was scanned on a IIa single-crystal diamond sample (4.5 × 4.5 × 0.5 mm3) to cause highly damaged sub-superficial structures that were defined with micrometric spatial resolution. After implantation, the sample was annealed. This process provides the conversion of the sub-superficial highly damaged regions to a graphitic phase embedded in a highly insulating diamond matrix. Thanks to a three-dimensional masking technique, the endpoints of the sub-superficial channels emerge in contact with the sample surface, therefore being available as sensing electrodes. Cyclic voltammetry and amperometry measurements of solutions with increasing concentrations of adrenaline were performed to characterize the biosensor sensitivity. The reported results demonstrate that this new type of biosensor is suitable for in vitro detection of catecholamine release