Al, Al/C and Al/Si implantations in 6H-SiC

Multiple-energy Al implantations were performed with and without C or Si co-implantations into 6H-SiC epitaxial layers and bulk substrates at 850 degrees C. The C and Si co-implantations were used as an attempt to improve Al acceptor activation in SiC. The implanted material was annealed at 1500, 1600, and 1650 degrees C for 45 min. The Al implants are thermally stable at all annealing temperatures and Rutherford backscattering via channeling spectra indicated good lattice quality in the annealed Al-implanted material. A net hole concentration of 8 x 10(18) cm(-3) was measured at room temperature in the layers implanted with Al and annealed at 1600 degrees C. The C or Si co-implantations did not yield improvement in Al acceptor activation. The co-implants resulted in a relatively poor crystal quality due to more lattice damage compared to Al implantation alone. The out-diffusion of Al at the surface is more for 5Si co-implantation compared to Al implant alone, where 5Si means a Si/Al dose ratio of 5.