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 ∼106 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 × 1016cm–3) to high concentration (2.7 × 1018cm–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)