Interface metallization and electrical characterization of Ta-Pt multilayers on n-type SiC

A multilayered metallization Ta/Pt/Ta has been developed for obtaining low resistance ohmic contact to n-type SiC. The electrical, chemical and microstructural properties of the contacts are studied. It is observed that the conducting behavior is rectifying in the as-deposited state, whereas becomes ohmic upon annealing above 900 °C for 5 min in an Ar ambient, resulting in a typical specific contact resistance as low as 10−4 Ω cm2 range corresponding to a doping level of 2 × 1018 cm−3. The Auger electron spectroscopy (AES) and X-ray diffraction analysis results indicate that platinum atoms migrate towards SiC to form platinum silicides in intimate contact with SiC substrate. While the C atoms released from the SiC interface interact with out-diffused Ta atoms to form TaC at the contact surface. The addition of Ta into the Pt metallization scheme serves to reduce the residual carbon left behind from SiC dissociation and Pt-silicides formation, thus could lead to improvement of the thermal and electrical stability. Ta/Pt/Ta metallization on n-SiC is an effective method to realize ohmic contact.