Characterisation of deep level trap centres in 6H-SiC p-n junction diodes

Deep level transient spectroscopy (DLTS) measurements were performed on silicon carbide (6H-SiC) n+p−p+ junction diodes in order to compare the electrical properties and quality of epitaxial layers in the implanted and the epitaxial emitter diodes, where the p−p+ layers are the same. Four hole trap centres were detected on the implanted emitter diodes. Their thermal activation energy’s are 0.49, 0.6, 0.7 and 0.87 eV, respectively, referred to the valence band. The last three trap centres are also observed on the epitaxial emitter diodes. The origin of deep levels, with Ea=0.7 and 0.87 eV, is still under investigation. The thermal activation energy and capture cross section (0.6 eV, 4.3×10−15 cm2) is in good agreement with values reported for the boron-related D-centre. The trap centre with Ea=0.49 eV is associated to the ion-implantation process of the n+ layer. Double deep level transient spectroscopy measurements (DDLTS) have been performed to accurately profile this last defect through the depletion region. Its trap concentration NT(x) as a function of the depletion region width indicates that this defect is located near the n+/p− junction.