Fabrication of 2700-V 12- $\hbox {m}\Omega \cdot \hbox {cm}^{2}$ Non Ion-Implanted 4H-SiC BJTs

High-voltage blocking (2.7-kV) implantation-free SiC bipolar junction transistors with low ON-state resistance (12 mOmegaldrcm²) and high common-emitter current gain of 50 have been fabricated. A graded-base doping was implemented to provide a low-resistive ohmic contact to the epitaxial base. This design features a fully depleted base layer close to the breakdown voltage providing an efficient epitaxial JTE without ion implantation. Eliminating all ion implantation steps in this approach is beneficial for avoiding high-temperature dopant activation annealing and for avoiding generation of lifetime-killing defects that reduce the current gain.