Interface Reactions and Electrical Properties of Ta/4H-SiC Contacts

Abstract

This study deals with the interfacial reactions and electrical properties of Ta/4H-SiC contacts. Tantalum thin films (~100 nm) were deposited onto SiC wafer at room temperature by argon ion beam sputtering. The samples were then heated in high vacuum at 650°C, 800°C or 950°C for 30 min. X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (XRD), Auger electron spectroscopy (AES) and current-voltage (I-V) technique were used for characterising the samples. Ohmic contact is formed in the studied samples after annealing at or above 800°C even though considerable amount of metallic Ta still exists. The reaction zone possesses a layered structure of Ta2C/Ta2C+Ta5Si3/SiC. High enough temperature is needed to provide for sufficient interface change to tailor the contact properties.