Abstract
Characteristics of ohmic Co/Si/Co contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Co/Si/Co sputtered sequentially. The annealings were performed at $800^{\circ}C$ using RTP in vacuum ambient and $Ar:H_2$(9:1) ambient, respectively. The specific contact resistivity$(\rho_c)$, sheet resistance$(R_s)$, contact resistance$(R_c)$, transfer length$(L_T)$ were calculated from resistance$(R_T)$ versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were $\rho_c=1.0{\tiimes}10^{-5}{\Omega}cm^2$, $R_c=20{\Omega}$ and $L_T$ = 6.0 those of sample annealed at $Ar:H_2$(9:1) ambient were $\rho_c=4.0{\tiimes}10^{-6}{\Omega}cm^2$, $R_c=4.0{\Omega}$ and $L_T$ = 2.0. The physical properties of contacts were examined using XRD and AES. The results showed that cobalt silicide was formed on SiC and Co was migrated into SiC.
