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4H-SiC based p-n junction UV photo-detectors were irradiated with 600 keV He+ in the fluence range of 5 × 1011 ÷ 5 × 1014 ion/cm2 in order to investigate their radiation hardness. The effects of irradiation on the electro-optical performance were monitored in dark condition and in the UV (200 ÷ 400 nm) range, as well as in the visible region confirming the typical visible blindness of unirradiated and irradiated SiC photo-sensors. A decrease of UV optical responsivity occurred after irradiation and two fluence regimes were identified. At low fluence (13 ions/cm2), a considerable reduction of optical responsivity (of about 50%) was measured despite the absence of relevant dark current changes. The presence of irradiation induced point defects and then the reduction of photo-generated charge lifetime are responsible for a reduction of the charge collection efficiency and then of the relevant optical response reduction: point defects act as recombination centers for the photo-generated charges, which recombine during the drift/diffusion toward the electrodes. At higher irradiation fluence, the optical responsivity is strongly reduced due to the formation of complex defects. The threshold between low and high fluence is about 100 kGy, confirming the radiation hardness of SiC photo-sensors.

Self-organization is a phenomenon that occurs under certain circumstances with different types of materials – liquids, bulk, and thin films, organic, inorganic or hybrid solids. This unique effect ...

The INFN-CIMA project deals with the employment of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) for applications in Nuclear Physics. In particular, the project aim is that to use ...

Silicon carbide (SiC) is an attractive material for power devices owing to the availability of high-quality epitaxial wafers and superior physical properties, such as its high breakdown electric field strength, high electron mobility, and low anisotropy. Ion implantation is a key process for both n- and p-type selective doping of SiC devices. A subsequent annealing in the temperature range of 1600- 1800°C is required to remove the damage induced by the implantation process and to electrically activate the implanted dopants. The aim of this work is the investigation of the effect of thermal annealing on the damage induced by Phosphorous ion implantation to produce n-type regions.

In this study, 4H-SiC p–n junctions were irradiated with 700 keV He+ ions in the fluence range 1.0 × 1012 to 1.0 × 1015 ions/cm2. The effects of irradiation were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements, while deep-level transient spectroscopy (DLTS) was used to study the traps introduced by irradiation defects. Modifications of the device’s electrical performances were observed after irradiation, and two fluence regimes were identified. In the low fluence range (£1013 ions/cm2), I–V characteristics evidenced an increase in series resistance, which can be associated with the decrease in the dopant concentration, as also denoted by C–V measurements. In addition, the pre-exponential parameter of junction generation current increased with fluence due to the increase in point defect concentration. The main produced defect states were the Z1/2, RD1/2, and EH6/7 centers, whose concentrations increased with fluence. At high fluence (&gt, 1013 ions/cm2), I–V curves showed a strong decrease in the generation current, while DLTS evidenced a rearrangement of defects. The detailed electrical characterization of the p–n junction performed at different temperatures highlights the existence of conduction paths with peculiar electrical properties introduced by high fluence irradiation. The results suggest the formation of localized highly resistive regions (realized by agglomeration of point defects) in parallel with the main junction.

We propose a Near Infra Red photon emitting 4H-SiC compact vertical pn diode. The “as fabricated” diode exhibits a strong visible emission at 500 nm associated with the intrinsic and/or processing induced D1 centers in the semiconductor. Thanks to opportune He+ ion irradiation, we are able to obtain color centers in the junction region responsible for photon emission around 900 nm while simultaneously quenching unwanted visible emission. Electro-optical investigation was conducted by Electro-Luminescence measurements in the 300 nm −1100 nm range and by Emission Microscopy, both with pumping a current between of 0.1 and 2 mA. The proportionality of the emission intensity to the pumping current opens the interesting perspective of engineering the concentration of defects with the aim of obtaining single defects and thus single photon source devices. This is of considerable interest in low-power proximity sensors for consumer, industrial, automotive and telecommunications applications.

Domain boundaries (DBs) generated during the growth of cubic silicon carbide (3C-SiC) on (001) Si and their interaction with stacking faults (SFs) were studied in this work. Direct scanning transmi...

SiC Schottky detectors, having a superficial active zone up to 80 micron depths and a thin surface metallization, are adapt to detect high energetic ions. In order to demonstrate their detection ability with high-energy resolution, a helium Rutherford backscattering spectroscopy (RBS) was employed to evaluate their detection efficiency, energy resolution in the region 1.0 – 6.0 MeV alpha ions, depth resolution and dependence on the ion beam current. The detector parameters dependencies on the surface passivation layers, ion energy and current are presented. The comparison of RBS analysis using a traditional barrier silicon detector is investigated, and the differences with SiC detector is presented and discussed.

We report on the structure of the Ti3InC2 (M3AX2) thin nanocrystalline films (TNCFs) produced by ion beam sputtering of the Ti, In, and C targets with subsequent thermal annealing, and irradiation by 100 keV Ne+ ions with two different fluences of 1 · 1014 cm−2 and 1 · 1016 cm−2. The Ti3InC2 TNCFs were characterized by a set of microscopic techniques (AFM, STEM/EDS, and HRTEM) as well ion beam analytical methods RBS and NRA. The STEM/EDS analysis revealed that the structure and chemical composition of the Ti3InC2 TNCF remained intact after irradiation with the lower fluence of 1 · 1014 cm−2 Ne+. However, a significant morphological instability was observed after irradiation with the higher fluence of 1 · 1016 cm−2 Ne+. The simulation of the nanobeam electron diffraction (NBED) patterns by using CrystalMaker code has pointed at the existence of new e-Ti2C0.06 (MXene) structures and separation of Indium (In) from the Ti3InC2 matrix. The analysis by nanoindentation showed that the irradiated Ti3InC2 TNCFs exhibited promising mechanical properties considering Young's modulus and hardness even for the locally disordered structure. M3AX2 TNCFs are a new type of 2D materials designed for applications in extreme environments, such as nuclear facilities with intensive radiation fields. However, the research is still in its infancy and requires further study on the synthesis of high-quality, dense, and homogeneous M3AX2 TNCFs. This work is an initial study related to the radiation resistance of Ti3InC2 TNCFs.

The assessment of the iodine status of natural waters is crucial for focusing future strategies for controlling and monitoring iodine deficiency disorders (IDD). Nanoparticles have been increasingly used as sensors for several organic and inorganic analytes. In this study, we report the synthesis of new Tyrosine Capped Anisotropic Silver Nanoparticles (AgNPs). The AgNPs were characterized by TEM, UV–vis spectroscopy, and polarized and depolarized dynamic light scattering measurements, and were used for the quantitative determination of iodide ions in the presence of excess chloride ions. Both anions gave rise to an etching of the tips of the nanoprims converting them in rounded nanoplates. However, iodide ions perform this etching much better than chloride ones, allowing for their selective determination in tap waters. Fluoride and bromide anions give rise to a more efficient etching than chloride ions, but their presence does not interfere with iodide determination. This method was also used to determine the concentration of iodide in a sample of drinking water.

This work describes the development of a new method for ion implantation induced crystal damage recovery using multiple XeCl (308 nm) laser pulses with a duration of 30 ns. Experimental activity was carried on single phosphorus (P) as well as double phosphorus and aluminum (Al) implanted 4H-SiC epitaxial layers. Samples were then characterized through micro-Raman spectroscopy, Photoluminescence (PL) and Transmission Electron Microscopy (TEM) and results were compared with those coming from P implanted thermally annealed samples at 1650&ndash, 1700&ndash, 1750 &deg, C for 1 h as well as P and Al implanted samples annealed at 1650 &deg, C for 30 min. The activity outcome shows that laser annealing allows to achieve full crystal recovery in the energy density range between 0.50 and 0.60 J/cm2. Moreover, laser treated crystal shows an almost stress-free lattice with respect to thermally annealed samples that are characterized by high point and extended defects concentration. Laser annealing process, instead, allows to strongly reduce carbon vacancy (VC) concentration in the implanted area and to avoid intra-bandgap carrier recombination centres. Implanted area was almost preserved, except for some surface oxidation processes due to oxygen leakage inside the testing chamber. However, the results of this experimental activity gives way to laser annealing process viability for damage recovery and dopant activation inside the implanted area.

In this paper, we present the extensive characterization of large-area silicon carbide-based UV sensors candidate for outdoors spectroscopic applications of gas or liquid. The proposed SiC Schottky devices exhibit a dark current density of 0.12 nA/cm(2) at 15 V, a 0.12-A/W responsivity at 300 nm, optimal visible blindness, and a switching time of similar to 190 ns. Effects of temperature on the sensor performance, of crucial interest for outdoors applications, are also examined in the range from -20 degrees C to 90 degrees C.

A Silicon carbide detector, based on a Schottky diode technology with an interdigitated front electrode design, was employed to monitor photons and low-energy ions. Photons were generated by a He-Cd laser with maximum optical power density of 64 mW/cm2, while a plasma generated by a pulsed laser at low intensity (1010 W/cm2), was used to produce low-energy Al and C ions. The measured detector yield in the case of the photon detection increases linearly with the optical power density, and shows saturation at high power densities, being the saturation value depending on the applied detector bias. A similar behavior is observed for ion detection, where the detector response saturates with increasing ion energy. Carrier generation rate was extracted from the experimental data obtaining almost equal values for photon and ion irradiations, allowing also to extract a maximum generation rate of about $8 \times 10^{19}$ carriers/cm $^{3}\cdot \text {s}$ as upper limit for the linear operation of the detector.

X-ray emission from laser generated plasma was studied at low (1010 W/cm2) and high (1018 W/cm2) intensity using ns and fs laser, respectively. Plasma characteristics were controlled trough the laser parameters, the irradiation conditions and the target properties. The X-ray spectra were acquired using fast detection technique based on SiC diodes with different active regions. The X-ray yield increases with the atomic number of the target, both at low and high intensity, and a similar empirical law has been obtained. The X-ray emission mechanisms from plasma are correlated to the plasma temperature and density and to the Coulomb charge particle acceleration, due to the charge separation effects produced in the non-equilibrium plasma. Functional dependences, theoretical approaches and interpretation of possible mechanism will be presented and discussed.

SiC detectors based on Schottky diodes with an interdigit or a thin continuous front electrode are employed for the characterization of plasma generated by low intensity (1010 W/cm2) laser were photons, electrons and keV ions are produced. The exposure to plasma induces the formation on the detector surface of debris and/or micrometric clusters of the target material whose concentration increases with the number of laser shots, leading to the formation of nanometric film after long exposure time. The presence of this deposit strongly modifies the electrical characteristics, the optical response and ion detection properties of the detectors. In particular, we monitored the current-voltage characteristics of SiC devices and we observed an increase of the leakage current, a decrease of the Schottky barrier height and a reduction of the photon detection efficiency in the UV region, by increasing the number of plasma shots. The modification in the electrical and optical properties have been observed after a high number of laser shots, and a simple cleaning procedure allows to remove the surface deposit and, in the case of the continuous front electrode device, to restore the initial electro-optical device performances. The differences related to geometry of the front electrode are discussed.

Silicon-Carbide detectors are extensively employed as diagnostic devices in laser-generated plasma, allowing the simultaneous detection of photons, electrons and ions, when used in time-of-flight configuration. The plasma generated by high intensity laser (1016 W/cm2) producing high energy ions was characterized by SiC detector with a continuous front-electrode, and a very thick active depth, while SiC detector with an Interdigit front-electrode was used to measure the low energy ions of plasma generated by low intensity laser (1010 W/cm2). Information about ion energy, number of charge states, plasma temperature can be accurately obtained. However, laser exposure induces the formation of surface and bulk defects whose concentration increases with increasing the time to plasma exposure. The surface defects consist of clusters with a main size of the order of some microns and they modify the diode barrier height and the efficiency of the detector as checked by alpha spectrometry. The bulk defects, due to the energy loss of detected ions, strongly affect the electrical properties of the device, inducing a relevant increase of the leakage (reverse) current and decrease the forward current related to a deactivation of the dopant in the active detector region.

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance.

Silicon carbide is a very promising material for next generation nuclear physics experiments at high beam luminosity. Such activities require devices able to sustain high fluxes of particles (up to 1014 ions/cm2) in order to determine the cross sections of very rare nuclear phenomena. One of these activities is the NUMEN project, which aims, through the double charge exchange reactions, to impact in the determination of nuclear matrix elements entering in the expression of half-life of the neutrino-less double beta decay. Due to the very low cross sections, these features can just be explored at fluences which exceed by far those tolerated in state of the art solid state detectors, typically used in this kind of experiments. The SiC technology offers today an ideal response to such challenges, giving the opportunity to cope the excellent properties of silicon detectors with the radiation hardness, thermal stability and visible blindness of SiC material.

Advanced targets based on Au nanoparticles embedded in polymers films show high absorption coefficient in the UV–visible and infrared region. They can be employed to enhance the proton and ion acceleration from the laser-generated plasma in TNSA regime. In conditions of “p” polarized laser irradiations at 1015 W/cm2 intensity, in these films can be induced resonant absorption due to plasma wave excitation. Plasma on-line diagnostics is based on SiC detectors, Thomson spectrometry and X-ray streak camera imaging. Measurements of kinetic energy of accelerated ions indicate a significant increment using polymer targets containing gold nanoparticles and “p” polarized laser light with respect to pure polymers and unpolarized light irradiation.

4H-SiC silicon carbide (SiC) Schottky diodes, with a 25 μm thick n-type epitaxial active layer and a very thin front electrode contact are studied and proposed for the detection of low energetic ions. For a first evaluation of the detection properties of the SiC detectors, a standard alpha emitting radiation source was used obtaining an energy resolution of 0.85% at 5.15 MeV energy. Then the devices were employed to monitor low energetic alpha particles. From these tests it was found that the 4H-SiC diodes are able to monitor the alpha particles backscattered by different single and multilayers metallic targets (Au, Ag, Cu on Si substrates) in the energy range between 300 keV and 600 keV. In this energy range a linear energy response and a good energy resolution, close to those of a traditional commercial silicon detector, were obtained. The possibility to use these detectors for material analysis and for plasma monitoring is also discussed.

DNA/ZnO nanoparticles were obtained by using a biopolymer-assisted chemical bath growth process. A dynamic light scattering (DLS) technique was used to investigate the size and the growth kinetics of the nanoparticles and scanning electron microscopy (SEM) was used to characterize their morphology. The obtained nanoparticles were larger than the original DNA molecules indicating that DNA acted as a template for the growth of asymmetric DNA/ZnO nanoparticles. The growth kinetics and the particle size were tuned with the solution temperature and composition. Thus, the DNA characteristics can be used to build up different supra-molecular objects by covering with nano ZnO the different polynucleotide structures present in solution. The implications of this process have several positive benefits for building nano-scale device.

The ion streams emitted from laser generated plasmas and post-accelerated through a high voltage acceleration path, were monitored by solid state 4H-SiC interdigit detectors in time-of-flight configuration. The plasmas are produced by irradiation of an aluminum target through a ns pulsed laser with 10 10 W/cm 2 intensity and 200 mJ pulse energy. Laser-generated plasma exhibits a mean energy of the order of 100 eV per amu. In order to enhance the ion kinetic energy a post acceleration in the range 1 kV–30 kV was employed. In this paper we studied the correlation of the acquired spectra shape with the post acceleration voltage and with the detector polarization condition. An increase in the spectra intensity was observed and studied with increasing both detector reverse bias and post acceleration voltage. Obtained results demonstrate that interdigit 4H-SiC diodes with millimetric size, show a quite good efficiency for ion detection with energy higher than 5 keV and are very promising devices allowing, thanks to their millimetric size, to carry out detectors array systems for the measurement of the spatial distribution of low energy ions generated by pulsed laser-plasmas.

In this experiment the absorption of the laser radiation impinging on polymeric films with Au nanoparticles implanted in surface was studied. By varying the polarization and the incidence angle of the laser radiation on target, the role in the laser absorption of both excitation of surface plasmons and excitation of electronic plasma waves at critical density through resonant absorption was highlighted. In conditions of p-polarized laser irradiations at 10 15 W / cm 2 intensity, resonant absorption can be induced in films enhancing proton and ion acceleration. Plasma on-line diagnostics is based on SiC detectors. Measurements of kinetic energy of accelerated ions indicate a significant increment using p-polarized laser light with respect to no-polarized light irradiation.

Proton beam writing technique was recently introduced at 3MV Tandetron accelerator at Nuclear Physics Institute in Rez (Czech Republic). It has been used, to produce three-dimensional (3D) micro-structures in poly(methylmethacrylate) by 2.0 MeV and 2.6 MeV protons micro-beam. Micro-channels (52 μm × 52 μm) have been realized. After chemical etching, the quality of the bottom and side walls of the produced structures in PMMA were analyzed using Scanning Transmission Ion Microscopy (STIM).

Nanostructured targets, based on hydrogenated polymers with embedded nanostructures, were prepared as thin micrometric foils for high-intensity laser irradiation in TNSA regime to produce high-ion acceleration. Experiments were performed at the PALS facility, in Prague, by using 1315 nm wavelength, 300 ps pulse duration and an intensity of 1016 W/cm2 and at the IPPLM, in Warsaw, by using 800 nm wavelength, 40 fs pulse duration, and an intensity of 1019 W/cm2. Forward plasma diagnostic mainly uses SiC detectors and ion collectors in time of flight (TOF) configuration. At these intensities, ions can be accelerated at energies above 1 MeV per nucleon. In presence of Au nanoparticles, and/or under particular irradiation conditions, effects of resonant absorption can induce ion acceleration enhancement up to values of the order of 4 MeV per nucleon.

SiC detectors based on Schottky barrier junction with depletion layer of about 60 μm can be employed to monitor the radiations emitted from laser-generated plasmas. On the base of the detector geometry UV and X-rays, ions and electrons can be detected with high efficiency at energies of the order of 10 keV, 1-100 MeV and 100 keV respectively. Detector response is proportional to the energy deposited in the depletion layer with an energy resolution comparable with the traditional Silicon detectors. The use of time-of-flight (TOF) techniques permits to measure the velocity of electrons and ions also in condition of low detection efficiency. Such detectors can be employed with success for fast plasma diagnostics detecting photons, electrons and ions. Measurements of SiC characterization, by using calibrated X-rays, electrons and ion sources and laser-generated plasmas, at intensity raging between 1010 Wcm−2 and 1016 Wcm−2, will be presented and discussed.

The thermal evolution of defects induced in 4H–SiC by multiple implantation of C ions was investigated by Low Temperature Photoluminescence in the temperature range 450–1000 K. The photoluminescence spectra show sharp luminescent lines (alphabet lines) in the wavelength range 426–440 nm upon irradiation and thermal treatment at 450 K induces the appearance of a new line at 427 nm ( D I centre). The trend shown by the luminescence lines as a function of the temperature is quite complex. The alphabet lines intensity increases up to 850 K, whereas at higher temperature decreases with an activation energy of 2.0 eV, suggesting that the defect, responsible for these lines, is the Si-vacancy. The luminescence yield of D I centre is always increasing as a function of the temperature, with a higher slope from 750 K, suggesting a correlation to the reconfiguration and to the annealing of point defects.

Gold nanoparticles solution prepared in water by laser ablation at 1064 nm of a gold metal plate was characterized by dynamic light scattering and UV–vis spectroscopy. Polarized dynamic scattering allows the measurement of translational diffusivity of Au nanoparticles, while depolarized scattering yields simultaneously the characterization of translational and rotational diffusivities. From these measurements the size and shape of Au nanoparticles are determined. Dynamic light scattering yields an average radius of 32 nm for the spherical nanoparticles in as prepared solution. The same measurements performed in an aged solution reveal the formation of ellipsoidal nanoparticles with minor and major semi-axis of 36 nm and 69 nm, respectively. The measured values allow to fit the UV–vis spectra with the Mie-Gans model and to measure the concentration of Au nanoparticles obtaining a complete characterization of their nanostructure. Dynamic light scattering results a powerful technique to characterize the size and shape of gold nanoparticles.

Point defects induced in SiC by ion irradiation show a recombination at temperatures as low as 320 K and this process is enhanced after running current density ranging from 80 to 120 A/cm 2 . Ion irradiation induces in SiC the formation of different defect levels and low-temperature annealing changes their concentration. Some levels ( S 0 , S x and S 2 ) show a recombination and simultaneously a new level ( S 1 ) is formed. An enhanced recombination of defects is besides observed after running current in the diode at room temperature. The carriers introduction reduces the S 2 trap concentration, while the remaining levels are not modified. The recombination is negligible up to a current density of 50 A/cm 2 and increases at higher current density. The enhanced recombination of the S 2 trap occurs at 300 K, which otherwise requires a 400 K annealing temperature. The process can be related to the electron–hole recombination at the associated defect.

The defects produced in 4H–SiC epitaxial layers by irradiation with a 200 keV H + ion beam in the fluence range 6.5 × 10 11 –1.8 × 10 13 ions/cm 2 are investigated by Low Temperature Photoluminescence (LTPL–40 K). The defects produced by ion beam irradiation induce the formation of some sharp lines called “alphabet lines” in the photoluminescence spectra in the 425–443 nm range, due to the recombination of excitons at structural defects. From the LTPL lines intensity trend, as function of proton fluence, it is possible to single out two groups of peaks: the P 1 lines ( e , f , g ) and the P 2 lines ( a , b , c , d ) that exhibit different trends with the ion fluence. The P 1 group normalized yield increases with ion fluence, reaches a maximum at 2.5 × 10 12 ions/cm 2 and then decreases. The P 2 group normalized yield, instead, exhibits a formation threshold at low fluence, then increases until a maximum value at a fluence of 3.5 × 10 12 ions/cm 2 and decreases at higher fluence, reaching a value of 50% of the maximum yield. The behaviour of P 1 and P 2 lines, with ion fluence, indicates a production of point defects at low fluence, followed by a subsequent local rearrangement creating complex defects at high fluence.

The defects produced by 7.0 MeV C + irradiation in 4H-SiC epitaxial layer were followed by Deep Level Transient Spectroscopy, current-voltage measurements and Transmission Electron Microscopy in a large fluence range (10 9-5?ó10 13 ions/cm 2). At low fluence (10 9 -10 10 ions/cm 2), the formation of three main level defects located at 0.68 eV, 0.98 eV and 1.4 eV below the conduction band edge is detected. The trap concentration increases with ion fluence suggesting that these levels are associated to the point defects generated by ion irradiation. In this fluence range the leakage current of the diodes does not change. At higher fluence an evolution of defects occurs, as the concentration of traps at 0.68 eV and 1.4 eV decreases, while the intensity of the level at 0.98 eV remains constant. In this fluence range complex defects are formed and an increase of a factor five in the leakage current is measured. ¬© (2009) Trans Tech Publications.

The low temperature evolution of point defects induced in SiC by ion irradiation was investigated by deep level transient spectroscopy. The defects were introduced by irradiation with a 7.0 MeV beam of C+ ions at a fluence of 6 × 109 cm− 2. Annealing was then performed in the temperature range of 330–400 K in order to study the change in point defect structure with temperature. The low temperature annealing performed was observed to induce a change in the produced defects. The deep levels related to the Sx (EC − 0.6 eV) and S2 defects (EC − 0.7 eV) recovered with annealing while, simultaneously, a new level, S1 (EC − 0.4 eV), was formed. The activation energy of the S1 defect is 0.94 eV, while the annealing of both the Sx and S2 levels occurred with activation energy of 0.65 eV.

The defects produced by irradiation with 7 MeV C+ induce a change in the electrical properties of 4H-SiC Schottky diodes. Capacitance-voltage and Current-voltage characteristics of the diodes fabricated in epilayers doped with different nitrogen concentrations were monitored before and after irradiation with different fluences. The Capacitance-voltage curves show free carrier compensation after low fluence irradiation and it was found that the reduction of carriers per ion induced vacancy increases with nitrogen content. The forward current-voltage characteristics of the diodes show an increase in the series resistance after irradiation. This change is mainly related to the high compensation occurring around the end of the ion range.

The growth rate of 4H-SiC epi layers has been increased up to 100 µm/h with the use of trichlorosilane instead of silane as silicon precursor. The epitaxial layers grown with this process have been characterized by electrical, optical and structural characterization methods. Schottky diodes, manufactured on the epitaxial layer grown with trichlorosilane at 1600 °C, have higher yield and lower defect density in comparison to diodes realized on epilayers grown with the standard epitaxial process.

High growth rate of 4H-SiC epitaxial layers can be reached with the introduction of HCl in the deposition chamber. The effect of the Cl/Si ratio on this epitaxial growth process has been studied by optical and electrical measurements. Optical microscopy shows an improvement of the surface morphology and luminescence measurements reveal a decrease of epitaxial layer defects with increasing the Cl/Si ratio in the range 0.05–2.0. The leakage current measured on the diodes realized on these wafers is reduced of an order of magnitude and DLTS measurements show a decrease of the EH6,7 level concentration in the same range of Cl/Si ratio. The value Cl/Si=2.0 allows to grow epitaxial layers with the lowest defect concentration.

The growth rate of 4H-SiC epi layers has been increased by a factor 19 (up to 112 μm/h) with respect to the standard process with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl have been characterized by electrical, optical and structural characterization methods. An optimized process without the addition of HCl is reported for comparison. The Schottky diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600 °C, have electrical characteristics comparable with the standard epitaxial process with the advantage of an epitaxial growth rate three times higher.

Nanoparticles have been increasingly used as sensors for several organic and inorganic analytes. In this work, we report a study on the synthesis of novel highly fluorescent l-Tyr capped silver nanoparticles (AgNPs) and their use for the determination of metal ions. The AgNPs have been characterized by TEM, UV–Vis and Photoluminescence (PL) spectroscopy and dynamic light scattering (DLS) measurements and used for the quantitative determination of Co(II) and Cu(II) ions. In the l-Tyr capped AgNPs, the α-amino and α-carboxyl groups of the surface-confined amino acid can coordinate the entitled metal ions, giving rise to a decrease of the silver surface plasmon absorption, that is linearly correlated with the metal ions concentrations. The addition of Co(II) and Cu(II) solutions to the l-Tyr AgNPs also induces a paramagnetic quenching of the fluorescence in the PL spectra and the related Stern Volmer plots highlight a linear correlation over the whole concentration range for both metal ions, with a more pronounced effect for the copper(II) ion.

Optical trapping of silver nanoplatelets obtained with a simple room temperature chemical synthesis technique is reported. Trap spring constants are measured for platelets with different diameters to investigate the size-scaling behaviour. Experimental data are compared with models of optical forces based on the dipole approximation and on electromagnetic scattering within a T-matrix framework. Finally, we discuss applications of these nanoplatelets for surface-enhanced Raman spectroscopy.

Polarized and depolarized dynamic light scattering (DDLS) methodology was carried out on silver nanoplatelets showing strong plasmon-enhanced scattering. The hydrodynamic properties of the nanoparticles were determined by measuring the translation diffusion coefficient for “out resonant” condition and the rotational diffusion coefficient for “in resonant” condition. The results have been interpreted by applying an oblate ellipsoidal model, which allows a direct evaluation of nanoplatelets’ size and shape in agreement with scanning electron microscopy. The characterised nanoplatelets reveal a transversal size of 20 nm and a longitudinal length in the range 65–92 nm. Our investigation shows that DDLS in resonant condition is a simple and powerful technique to determine the size and shape of plasmonic nanoparticles and it can be successfully applied to characterise the dynamics of metallic nanoplatelets.

The excellent physical and chemical properties and the radiation hardness of silicon carbide (SiC) render this material particularly suitable for the realization of radiation detectors. In this paper we describe the main properties of SiC and the processes needed to realize good performance detectors. To this purpose, we made SiC Schottky diodes that were electrical characterized by using different techniques. In order to test the radiation hardness, the diodes were irradiated with different ion beams and the analysis of the electrical measurements allowed to identify the defects responsible of the device degradation. These detectors have been used to monitor the multi-MeV ions of the plasma emitted by irradiation of various targets with 300-ps laser at high intensity (1016 W/cm2). These measurements highlighted that the use of SiC detectors enhances the sensitivity to ions detection due to the cutting of the visible and soft ultraviolet radiation emitted from plasma. The small rise time and the proportio...

The defects formation in ion-irradiated 4H-SiC was investigated and correlated with the electrical properties of Schottky diodes. The diodes were irradiated with 1 MeV Si+-ions, at fluences ranging between 1×109cm-2 and 1.8×1013cm-2. After irradiation, the current-voltage characteristics of the diodes showed an increase of the leakage current with increasing ion fluence. The reverse I-V characteristics of the irradiated diodes monitored as a function of the temperature showed an Arrhenius dependence of the leakage, with an activation energy of 0.64 eV. Deep level transient spectroscopy (DLTS) allowed to demonstrate that the Z1/Z2 center of 4H-SiC is the dominant defect in the increase of the leakage current in the irradiated material.