Determination of Schottky barrier height of graphene electrode on AlGaN/GaN heterostructure

A graphene Schottky contact was fabricated on an AlGaN/GaN heterostructure and subsequently analyzed. The calculated and experimentally measured Schottky barrier heights (SBHs) determined using the theoretical Schottky-Mott model, the thermionic emission model, the temperature-dependent current-voltage measurement, and the capacitance-voltage measurement were observed to be inconsistent, which was attributed to the ambiguities in both the Schottky contact area and the Richardson constant. While excluding the effects of these two factors, an SBH of 0.15 eV was determined by the temperature-dependent Richardson plot. This result was confirmed by calculating the inverse of the square of the measured capacitance with consideration of the threshold voltage required to deplete the two-dimensional electron gas under the Schottky contact.