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 × 10 16 cm –3 ) to high concentration (2.7 × 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). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)