Palladium Ohmic contact on hydrogen-terminated single crystal diamond film

• The adhesion of Pd is much better than Au on H-diamond.
• The Pd contact shows excellent thermal stability up to 700 °C.
• The minimum specific contact resistance is evaluated to be 4.93 × 10−7 Ω cm2 at 400 °C.
• The barrier height is − 0.15 eV and − 0.03 eV for as-deposited and annealed sample.
• HNO3 vapor surface treatment before evaporation is found to reduce the specific contact resistance.

Contact properties of Palladium (Pd) on the surface of hydrogen-terminated single crystal diamond were investigated with several treatment conditions. 150 nm Pd pad was deposited on diamond surface by thermal evaporation technique, which shows good Ohmic properties with the specific contact resistivity (ρc) of 1.8 × 10− 6 Ω cm2 evaluated by Transmission Line Model. To identify the thermal stability, the sample was annealed in Ar ambient from 300 to 700 °C for 3 min at each temperature. As the temperature increased, ρc firstly decreased to 4.93 × 10−7 Ω cm2 at 400 °C and then increased. The barrier height was evaluated to be − 0.15 eV and − 0.03 eV for as-deposited and 700 °C annealed sample by X-ray photoelectron spectroscopy analysis. Several surface treatments were also carried out to determine their effect on ρc, among which HNO3 vapor treated sample indicates a lower value of 5.32 × 10−6 Ω cm2.