Palladium Ohmic contact on hydrogen-terminated single crystal diamond film

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 (ρ_c) 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, ρ_c 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 ρ_c, among which HNO₃ vapor treated sample indicates a lower value of 5.32 × 10^-6 Ω cm².