Investigation of Ni/Ta contacts on 4H silicon carbide

Journal article, 2007

Nickel and Tantalum thin films with 3:5 thickness ratios were deposited in succession onto 4H–SiC substrate at room temperature. The samples were then heated in situ in vacuum at 650, 800 or 950 8C for 30 min. Glancing angle X-ray diffraction (XRD), Auger electron spectroscopy (AES) and current–voltage (I–V) technique were used for characterising the interfacial reactions and electrical properties. Amorphous Ni–Ta can be formed by solid-state reaction at 650 8C. The minor dissolved Ni in the Ta metal promotes the reaction between Ta and SiC. With increasing annealing temperature up to 950 8C, the dominant carbide changes from Ta2C to TaC and a layer structure is developed. Electrical measurements show that ohmic contact is formed after annealing at or above 800 8C.