Electrical characterization of annealed Ti/TiN/Pt contacts on N-type 6H-SiC epilayer

Abstract

We report results of the electrical characteristics of in vacuo deposited Ti/TiN/Pt contact metallization on n-type 6H-SiC epilayer as 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 are rectifying, except for the highly doped sample. Only the lesser doped remains rectifying after samples are annealed at 1000/spl deg/C between 0.5 and 1 min 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 0.54-0.84 eV are obtained. Adhesion problems associated with metal deposition on pre-processed titanium is not observed, leading to excellent mechanical stability. Auger electron spectroscopy (AES) reveals the out diffusion of Ti-Si and agglomeration of Ti-C species at the epilayer surface. The contact resistance remains appreciably stable after treatment in air at 650/spl deg/C for 65 h. The drop in SBH and the resulting stable contact resistance is proposed to be associated with the thermal activation of TiC diffusion barrier layer on the 6H-SiC epilayer during annealing.