Low Resistance Ohmic Contacts to Bi[sub 2]Te[sub 3] Using Ni and Co Metallization

A detailed study of the impact of surface preparation and postdeposition annealing on contact resistivity for sputtered Ni and Co contacts to thin-film is presented. The specific contact resistivity is obtained using the transfer length method. It is observed that in situ sputter cleaning using Ar bombardment before metal deposition gives a surface free of oxides and other contaminants. This surface treatment reduces the contact resistivity by more than 10 times for both Ni and Co contacts. Postdeposition annealing at on samples that were sputter-cleaned further reduces the contact resistivity to for both Ni and Co contacts to . Co as a suitable contact metal to is reported. Co provided similar contact resistance values as Ni, but had better adhesion and less diffusion into the thermoelectric material, making it a suitable candidate for contact metallization to based devices.