Electrical characteristics of n-type diamond Schottky diodes and metal/diamond interfaces

Electrical characteristics of n-type diamond Schottky diodes and metal/diamond interfaces have been systematically investigated for phosphorus (P)-doped homoepitaxial diamond layers. The current-voltage (I-V) characteristics of the Ni/n-type diamond Schottky diode show excellent rectification properties from 297 K to 773 K. The ideality factor and the rectification ratio were 1.0 and ∼10 6 at +10 V at 573 K, respectively. The rectifying properties deteriorated with increasing P concentration in the diamond layers. Temperature-dependent capacitance-frequency (C-f) and conductance-frequency (G-f) measurements on the Schottky diodes have shown that the capacitance is reduced at high frequency due to the inability of deep centers to maintain an equilibrium ionization state under a high-frequency modulation. C- V measurements deduced that the P electrical activity (the ratio of the net donor concentration to the P concentration) was nearly 1 from low concentration (1.6 x 10 16 cm -3 ) to high concentration (2.7 x 10 18 cm -3 ) of P. The Schottky barrier height was found to be almost constant at ∼4.3 eV independent of the metal work function (Ni, Pt, Al and Ti).