The effects of different anode manufacturing methods on deep levels in 4H-SiC p+n diodes

Abstract

The manufacture of bipolar junctions is necessary in many 4H-SiC electronic devices, e.g., junction termination extensions and p+in diodes for voltage class >10 kV. However, the presence of electrically active levels in the drift layer that act as minority charge carrier lifetime killers, like the carbon vacancy (VC), undermines device performance. In the present study, we compared p+n diodes whose anodes have been manufactured by three different methods: by epitaxial growth, ion implantation, or plasma immersion ion implantation (PIII). The identification of the electrically active defects in the drift layers of these devices revealed that a substantial concentration of VC is present in the diodes with epitaxial grown or ion implanted anode. On the other hand, no presence of VC could be detected when the anode is formed by PIII and this is attributed to the effects of strain in the anode region. Our investigation shows that PIII can be a useful technique for the manufacture of bipolar devices with a reduced concentration of lifetime killer defects.