Characterization of Ti/TiN/Pt contacts on n-type 6H-SiC epilayer at 650/spl deg/C

We report results of electrical characteristics of Ti/TiN/Pt contact metallization on n-type 6H-SiC epilayer as a function of impurity concentration in the range of 3.3/spl times/10/sup 17/ cm/sup -3/to 1.9/spl times/10/sup 19/ cm/sup -3/. The as-deposited contacts were rectifying, except for the highly doped sample. Only the lesser doped remained rectifying after samples were annealed at 1000/spl deg/C between .5 to 1 minute in argon. Bulk contact resistance ranging from factors of 10/sup -5/ to 10/sup -4/ /spl Omega/-cm/sup 2/ and Schottky barrier height in the range of 0.74 to 1.07 eV were obtained. The contact resistance remained appreciably stable after heat treatment at 650/spl deg/C in air for sixty-five hours. Adhesion problems associated with metal deposition on pre-processed titanium layer was not observed, indicating excellent mechanical stability. Auger electron spectroscopy (AES) revealed the out-diffusion of titanium-silicon species and probable formation of titanium carbide as the new interface layer with the 6H-SiC epilayer.