Displacement current of Au/p-diamond Schottky contacts

In this study, the displacement current of Au/p-diamond Schottky contacts was studied by comparing them with low-Mg-doped p-GaN Schottky contacts. In the current-voltage (I-V) characteristics, the current was proportional to the voltage sweep speed at V >−1.5 V. The differential output waveform was obtained through AC operation. Therefore, the displacement current was dominant in the low voltage region where in the true current was extremely small due to the large Schottky barrier height of 1.57 eV. The memory effect, due to the charge and discharge of localized acceptor-type deep-level defects, was negligible in the I-V curve. A clear AC differential signal was confirmed. This suggested that the interface defect density of the p-diamond contacts was very small compared to the p-GaN contacts. Hence, p-diamond Schottky contacts were expected to be a good candidate for a key device such as a phase modulator in a wireless transmitter.