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 Asq.into the 4H-silicon carbide SiC. substrates with high dose of 7=1015 cmy2 has been investigated as an effective doping method of n-type dopant for SiC power electron devices fabrication. Regardless of the ion implantation temperature, the sheet resistances Rs.decrease below 16008C post-annealing and increase above 17008C as the post-annealing temperature increases. The low Rs value 213 VrI.is achieved in the sample implanted at 5008C and annealed at 16008C, an order of magnitude smaller than that implanted at room temperature RT.. Atomic force microscopy AFM.images 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 Asq dopant depth profiles of the sample implanted at 5008C do not change before and after the post-annealing. On the other hand, for the sample implanted at RT, the Asq concentration in the ion-implanted layer decreases due to the outer-diffusion. These results indicate that high-temperature ion implantation is an effective method to prevent the outer-diffusion of Asq dopants during high-temperature post-annealing. It is considered that these post-annealing temperature dependences are caused by the evaporation of SiC surface layer. q2000 Elsevier Science B.V. All rights reserved