Implantation-Free 4H-SiC Bipolar Junction Transistors with Double Base Epi-layers

摘要

This paper reports the first 4H-SiC power bipolar junction transistor (BJT) which is completely free of ion implantation and hence is free of the implantation-induced crystal damages and high-temperature activation annealing-induced surface roughness. The BJT is designed to have double epitaxial p-type base layers with the top layer more heavily doped for direct Ohmic contact formation while at the same time supporting a robust single-step junction termination extension without the need of ion implantation. The double layers create a built-in electric field in the base region which helps to speed up injected electrons across the base and leads to an improved BJT current gain.