1,281 research outputs found
Photo-physical properties of He-related color centers in diamond
Diamond is a promising platform for the development of technological
applications in quantum optics and photonics. The quest for color centers with
optimal photo-physical properties has led in recent years to the search for
novel impurity-related defects in this material. Here, we report on a
systematic investigation of the photo-physical properties of two He-related
(HR) emission lines at 535 nm and 560 nm created in three different diamond
substrates upon implantation with 1.3 MeV He+ ions and subsequent annealing.
The spectral features of the HR centers were studied in an "optical grade"
diamond substrate as a function of several physical parameters, namely the
measurement temperature, the excitation wavelength and the intensity of
external electric fields. The emission lifetimes of the 535 nm and 560 nm lines
were also measured by means of time-gated photoluminescence measurements,
yielding characteristic decay times of (29 +- 5) ns and (106 +- 10) ns,
respectively. The Stark shifting of the HR centers under the application of an
external electrical field was observed in a CVD diamond film equipped with
buried graphitic electrodes, suggesting a lack of inversion symmetry in the
defects' structure. Furthermore, the photoluminescence mapping under 405 nm
excitation of a "detector grade" diamond sample implanted at a 1x1010 cm-2 He+
ion fluence enabled to identify the spectral features of both the HR emission
lines from the same localized optical spots. The reported results provide a
first insight towards the understanding of the structure of He-related defects
in diamond and their possible utilization in practical applicationsComment: 9 pages, 3 figure
Gate-source distance scaling effects in H-terminated diamond MESFETs
In this paper, an analysis of gate-source and gate-drain scaling effects in MESFETs fabricated on hydrogen-terminated single-crystal diamond films is reported. The experimental results show that a decrease in gate-source spacing can improve the device performance by increasing the device output current density and its transconductance. On the contrary, the gate--drain distance produces less pronounced effects on device performance. Breakdown voltage, knee voltage, and threshold voltage variations due to changes in gate-source and drain-source distances have also been investigated. The obtained results can be used as a design guideline for the layout optimization of H-terminated diamond-based MESFETs
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
Spectrometric performances of monocrystalline artificial diamond detectors operated at high temperature
Measurement and modelling of anomalous polarity pulses in a multi-electrode diamond detector
In multi-electrode detectors, the motion of excess carriers generated by
ionizing radiation induces charge pulses at the electrodes, whose intensities
and polarities depend on the geometrical, electrostatic and carriers transport
properties of the device. The resulting charge sharing effects may lead to
bipolar currents, pulse height defects and anomalous polarity signals affecting
the response of the device to ionizing radiation. This latter effect has
recently attracted attention in commonly used detector materials, but different
interpretations have been suggested, depending on the material, the geometry of
the device and the nature of the ionizing radiation. In this letter, we report
on the investigation in the formation of anomalous polarity pulses in a
multi-electrode diamond detector with buried graphitic electrodes. In
particular, we propose a purely electrostatic model based on the
Shockley-Ramo-Gunn theory, providing a satisfactory description of anomalous
pulses observed in charge collection efficiency maps measured by means of Ion
Beam Induced Charge (IBIC) microscopy, and suitable for a general application
in multi-electrode devices and detectors.Comment: 8 pages, 4 figure
Lateral IBIC characterization of single crystal synthetic diamond detectors
In order to evaluate the charge collection efficiency (CCE) profile of single-crystal diamond devices based on a p-type/intrinsic/metal configuration, a lateral Ion Beam Induced Charge (IBIC) analysis was performed over their cleaved cross sections using a 2 MeV proton microbeam. CCE profiles in the depth direction were extracted from the cross-sectional maps at variable bias voltage. IBIC spectra relevant to the depletion region extending beneath the frontal Schottky electrode show a 100% CCE, with a spectral resolution of about 1.5%. The dependence of the width of the high efficiency region from applied bias voltage allows the constant residual doping concentration of the active region to be evaluated. The region where the electric field is absent shows an exponentially decreasing CCE profile, from which it is possible to estimate the diffusion length of the minority carriers by means of a drift-diffusion model. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry
CaracterÃsticas quÃmicas de frutas de cultivares de morangueiro de dias neutros sob duas coberturas plásticas.
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