Ultra-low resistivity Al+ implanted 4H–SiC obtained by microwave annealing and a protective graphite cap

In this work, we have employed a graphite cap for rapid microwave annealing of aluminum implanted 4H–SiC, in the temperature range of 1750–1900 °C, for 30 s durations. The graphite cap prevailed even for 1900 °C/30 s microwave annealing yielding a low surface roughness of 2.4 nm. Rutherford backscattering-channeling spectra indicated that 1900 °C microwave annealing is much more effective than 1800 °C/5 min conventional furnace annealing in not only alleviating the implantation-induced lattice damage but also in removing some of the defects introduced during growth of the 4H–SiC epi-layer used for the Al+ implantation. Van der Pauw–Hall measurements indicated an extremely low sheet resistance of 2.8 kΩ/□ for the 1900 °C/30 s annealing, which is about 5 times smaller than the sheet resistance measured on the 1800 °C/5 min conventional furnace annealed material.