Current-voltage (I-V) characteristics with variations of voltage sweep speed (v(sweep)) and changing sweep directions, and alternating current (AC) operation of low-Mg-doped p-GaN Schottky contacts were analyzed. In the I-V characteristics, conventional memory effect, due to carrier capture and emission from acceptor-type deep-level defects, was seen for all the measurement conditions. In addition, proportional relationship between vsweep and current, and polarity inversion of the current were observed when the applied voltage was low, which indicates the existence of a displacement current, because the Schottky barrier height is so high and a true current is significantly small. In the AC operations under the square- and sinusoidal-wave input, a conventional rectifying operation was observed when the input voltage was relatively high. However, we found differential operation in the output current when the input voltage was low, where the displacement current was dominant. Such a unique functional operation was achieved by only one Schottky diode. (c) 2013 Elsevier B.V. All rights reserved.