Capacitance-Voltage-Frequency Characteristics of Ni/Diamond Schottky Diodes on Oxidized Boron-Doped Homoepitaxial Diamond Film

The electrical properties of Ni/diamond Schottky diodes fabricated on oxidized boron-doped homoepitaxial diamond film have been studied in order to investigate the electrical behaviors of diamond-based electronic devices. The current-voltage (I-V) characteristics of the Ni-Schottky contacts to the boron-doped homoepitaxial diamond film show excellent rectification properties. The capacitance-voltage (C-V) features of the Ni/diamond Schottky diodes were characterized in the frequency range from 10-3 Hz to 2 x 105 Hz. The C-V measurements indicate that the space charge density (NI) and the diffusion potential (Vd) values are about 6.5 x 1016 cm-3 and 1.25 V, respectively, and have weak frequency dependence in the range from 10-3 Hz to 104 Hz. The capacitance-frequency measurement at zero bias indicated that the degrading capacitance at high frequency (>104 Hz) is primarily due to the high series resistance of the homoepitaxial diamond film. The sudden drop in capacitance with increasing forward bias (VF) observed in Ni/diamond Schottky diodes is an interesting feature which can be explained by the model proposed by A.J. Snell et al.