Reliable Ohmic Contact Properties for Ni/Hydrogen-Terminated Diamond at Annealing Temperature up to 900 °C

Ohmic contact with high thermal stability is essential to promote hydrogen-terminated diamond (H-diamond) electronic devices for high-temperature applications. Here, the ohmic contact characteristics of Ni/H-diamond at annealing temperatures up to 900 °C are investigated. The measured current–voltage curves and deduced specific contact resistance (ρC) are used to evaluate the quality of the contact properties. Schottky contacts are formed for the as-received and 300 °C-annealed Ni/H-diamonds. When the annealing temperature is increased to 500 °C, the ohmic contact properties are formed with the ρC of 1.5 × 10−3 Ω·cm2 for the Ni/H-diamond. As the annealing temperature rises to 900 °C, the ρC is determined to be as low as 6.0 × 10−5 Ω·cm2. It is believed that the formation of Ni-related carbides at the Ni/H-diamond interface promotes the decrease in ρC. The Ni metal is extremely promising to be used as the ohmic contact electrode for the H-diamond-based electronic devices at temperature up to 900 °C.