The post-annealing temperature dependences of electrical properties and surface morphologies for arsenic ion-implanted 4H-SiC at high temperature

High-temperature ion implantation of arsenic (As+) into the 4H-silicon carb ide (SiC) substrates with high dose of 7 x 10(15) cm(-2) has been investiga ted as an effective doping method of n-type dopant for SiC power electron d evices fabrication, Regardless of the ion implantation temperature, the she et resistances (R-s) decrease below 1600 degrees C post-annealing and incre ase above 1700 degrees C as the post-annealing temperature increases. The l ow R-s value (213 Omega/square) is achieved in the sample implanted at 500 degrees C and annealed at 1600 degrees C, an order of magnitude smaller tha n that implanted at room temperature (RT), Atomic force microscopy (AFM) im ages reveal that the surface roughness of ion-implanted SiC increases with the increase of post-annealing temperature. Secondary ion mass spectroscopy (SIMS) results show that As+ dopant depth profiles of the sample implanted at 500 degrees C do not change before and after the post-annealing. On the other hand; for the sample implanted at RT, the As+ concentration in the i on-implanted layer decreases due to the outer-diffusion. These results indi cate that high-temperature ion implantation is an effective method to preve nt the outer-diffusion of As+ dopants during high-temperature post-annealin g. It is considered that these post-annealing temperature dependences are c aused by the evaporation of SIC surface layer. (C) 2000 Elsevier Science B. V. All rights reserved.