Corrosion-Resistive and Low Specific Contact Resistance Ohmic Contacts to Semiconducting Diamonds Using Nanocarbon Electrodes

The realization of diamond-based advanced devices is interrelated with the fabrication of practical ohmic contacts. Contrary to boron-doped, the phosphorus-doped diamonds with interface carbide forming Ti-based conventional ohmic contacts find their limitation in device fabrication due to the high contact resistance. Herein, nanocarbon ohmic contacts are deposited by a coaxial arc plasma gun on semiconducting diamonds, and their composite structure which facilitates exceptional contact properties is explored. A comparative electrical characterization between nanocarbon ohmic contacts and conventional Ti-based contacts is performed on a heavily phosphorus-doped diamond, and they exhibited one-order declination in specific contact resistance. In addition to the low contact resistance, an ideal ohmic electrode is preferable to have good mechanical adhesion and corrosion resistance for device applications. The contact behavior of n-type diamond/nanocarbon against an extremely corrosive environment realized by boiling H₂SO₄ + HNO₃ solution is analyzed. The nanocarbon ohmic contacts exhibit excellent corrosion resistance and mechanical adhesion over conventional Ti-based contacts. A similar trend is also observed for nanocarbon contacts on boron-doped diamonds. The modest effect on the transfer length of the nanocarbon contacts with respect to acid treatment sessions indicates a tightly bonded diamond/nanocarbon interface and actively suggests their application in highly-corrosive and harsh environments.