Thermal stability investigation for Ohmic contact properties of Pt, Au, and Pd electrodes on the same hydrogen-terminated diamond

Here, thermal stabilities for Ohmic contact properties of Pt, Au, and Pd on the same hydrogen-terminated diamond (H-diamond) epitaxial layer are investigated. A long-term annealing process is performed with an annealing temperature and time of 400 °C and 8 h, respectively. Before annealing, good Ohmic contact properties are observed for only two contacts of the Pt/H-diamond and Pd/H-diamond with specific contact resistivity (ρC) values of 2.7 × 10−3 Ω cm2 and 2.6 × 10−4 Ω cm2, respectively. After long-term annealing, all three contacts on the H-diamond show good Ohmic contact properties. The ρC values for the Pt/H-diamond and Au/H-diamond are 3.1 × 10−2 Ω cm2 and 4.2 × 10−4 Ω cm2, respectively. They are higher than that of the Pd/H-diamond (1.1 × 10−4 Ω cm2). Therefore, low ρC and good thermal stability for the Pd/H-diamond are achieved. This is meaningful for pushing forward the development of H-diamond-based electronic devices for high-temperature applications.