Optical Characterization of 4H-SiC Thick Epitaxial Layer for Particle Detection

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 to obtain a 250 microns thick epi-layer. This sample will be used as particles detector in hostile environments such as neutron detection in a nuclear fusion reactor. Raman and Photoluminescence (PL) spectroscopy have been used to evaluate the quality of epitaxial layer observing the presence of long-range defects. With the support of the Time Resolved Photoluminescence, also important properties such as carrier lifetime and diffusion length were 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.