The purpose of this work is to study the 4H-SiC epitaxial layer properties for the fabrication of a device for neutron detection as an alternative material to diamond detectors used in this field. We have studied a high growth rate process to grow a thick epitaxial layer (250 µm) of 4H-SiC and, in order to estimate the quality of the epitaxial layer, an optical characterization was done through Photoluminescence (PL) spectroscopy for stacking fault defect evaluation. Micro Raman spectroscopy was used for simultaneous determination of both carrier lifetime and induced carriers in equilibrium. We have compared these results with other two samples with an epitaxial layer of 100 micron, obtained with two different growth rates, 60 and 90 µm/h, respectively. From Raman measurements it has been observed that both the growth rate and the grown epitaxial layer thickness have an effect on the measured carrier lifetime. A comparison between different kinds of stacking faults (SF) was done, evaluating the influence of these defects on the carrier lifetime as a function of the injection level and it was observed that only at a low injection is the effect on the carrier lifetime low.

In this work, 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 dark current density of 0.12 nA/cm2 @ 15 V, a 0.12 A/W responsivity @ 300 nm, optimal visible blindness and switching time of ~ 190 ns. Effects of temperature on the sensor performance, of crucial interest for outdoors applications, are also examined in the range from -20 °C to 90 °C.

The use of wide-band-gap solid-state neutron detectors is expanding in environments where a compact size and high radiation hardness are needed, such as spallation neutron sources and next-generation fusion machines. Silicon carbide is a very promising material for use as a neutron detector in these fields because of its high resistance to radiation, fast response time, stability and good energy resolution. In this paper, measurements were performed with neutrons from the ISIS spallation source with two different silicon carbide detectors together with stability measurements performed in a laboratory under alpha-particle irradiation for one week. Some consideration to the impact of the casing of the detector on the detector’s counting rate is given. In addition, the detector response to Deuterium-Deuterium (D-D) fusion neutrons is described by comparing neutron measurements at the Frascati Neutron Generator with a GEANT4 simulation. The good stability measurements and the assessment of the detector response function indicate that such a detector can be used as both a neutron counter and spectrometer for 2–4 MeV neutrons. Furthermore, the absence of polarization effects during neutron and alpha irradiation makes silicon carbide an interesting alternative to diamond detectors for fast neutron detection.

The aim of this work was a deep spectroscopical characterization of a thick 4H SiC epitaxial layer and a comparison of results between samples before and after a thermal oxidation process carried out at 1400 °C for 48 h. Through Raman and photoluminescence (PL) spectroscopies, the carrier lifetimes and the general status of the epilayer were evaluated. Time-resolved photoluminescence (TRPL) was used to estimate carrier lifetime over the entire 250 µm epilayer using different wavelengths to obtain information from different depths. Furthermore, an analysis of stacking fault defects was conducted through PL and Raman maps to evaluate how these defects could affect the carrier lifetime, in particular after the thermal oxidation process, in comparison with non-oxidated samples. This study shows that the oxidation process allows an improvement in the epitaxial layer performances in terms of carrier lifetime and diffusion length. These results were confirmed using deep level transient spectroscopy (DLTS) measurements evidencing a decrease in the Z_1/2 centers, although the oxidation generated other types of defects, ON1 and ON2, which appeared to affect the carrier lifetime less than Z_1/2 centers.

We propose a solid state based spectroscopy compact apparatus for monitoring environmental SO2, particularly suitable, for example, for volcanic applications. A prototype system, with a 170 mm long optical path, was assembled and tested using a commercial LED operating at 285 nm and a large area Silicon Carbide photodiode. Laboratory tests were carried out using calibrated quartz cuvettes containing SO2 at fixed concentrations and standard SO2 gas with 20% of O2 and complemented with N2 dry gas to fill the optical system chamber. Optical signal attenuations in the chemically interactive chamber follow the Beer-Lambert-Bouguer law in all the performed tests and a 0.16 ppm/pA ± 0.8 ppm nominal chemical resolution was obtained from the experimental data for the current prototype.

In the present work a deep characterization of 4H-SiC epi-layer was done. A thick layer was epitaxially grown through chemical vapor deposition (CVD) process in a horizontal hot-wall reactor in order to obtain a 250 microns thick epi-layer. This sample will be used as particle detector in hostile environments such as neutron detection in a nuclear fusion reactor. Raman and Photoluminescence (PL) spectroscopy have been used in order to evaluate the general status of epitaxy and, with the support of the Time Resolved Photoluminescence, also important properties such as carrier lifetime and diffusion length have been evaluated. Carrier lifetime evaluation before and after a thermal oxidation process at 1400° C for 48h was estimated, by considering a lifetime increment after oxidation process, due to the decrease of carbon vacancies. Finally, the influence of stacking fault (SF) defects on carrier lifetime was evaluated observing a decrease of the lifetime for the defects at 430 nm (2.88 eV) for both oxidated and non-oxidated samples.