Structural and electrical characterization of epitaxial 4H–SiC layers for power electronic device applications

In spite of the high potentiality of silicon carbide (SiC), its technology shows at the moment some limitations, due to the defects present in the crystalline structure. We have focused our analysis on commercial 4H–SiC epitaxial layers. A preliminary investigation has been performed by Optical and Scanning Electron microscopies with the aim to evidence the defect morphology on a large scale. An insight on the defect structure has been obtained by Atomic Force Microscopy, profilometer technique, Micro-Raman and Micro-Photoluminescence spectroscopies. Different types of defects such as comets, super dislocations, etch pits and so on, have been characterized finding interesting peculiarities such as different polytypes inclusions. Moreover, the influence of such defects on the SiC electrical performance has been deeply analyzed through the realization of Schottky barriers onto SiC regions including specific kinds of defects, then performing electrical characterization such as current–voltage (I–V) analysis. Deep Level Transient Spectroscopy (DLTS) yielded the energy position in the SiC gap, the concentration and the capture cross section of two center of recombination.