Reliability of metal-oxide-semiconductor capacitors on nitrogen implanted 4 H-silicon carbide

4H-SiC epitaxial layers were implanted with nitrogen up to doses of 1x1015 cm-2 and annealed at different temperatures. Atomic force microscopy revealed that the roughness of the SiC surface increased with the annealing temperature. It was shown that the oxide grows thicker on substrates with doping levels exceeding 1x1018 cm-3. The barrier height at the SiC/SiO2 interface, determined by voltage ramping on metal-oxide-semiconductor capacitors, decreased with increasing implantation dose. This decrease was attributed to residual implantation damage. Constant current injection experiments revealed an opposite charge buildup at the SiC/SiO2 interface for the highest implantation dose compared to samples with no implantation. It was shown that the breakdown behavior can be improved by annealing at 1700 degrees C compared to 1450 degrees C despite a higher surface roughness.