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Quasi-vertical gallium nitride (GaN) Schottky diodes on silicon carbide (SiC) substrate were fabricated for frequency multipliers applications. The epitaxial structure employed had a nlayer of 590 nm with doping 6.6 × 10 16 cm -3 , while the n + layer was 950 nm thick, with doping 2 × 10 19 cm -3 . Potassium hydroxide (KOH) chemical surface treatment before Schottky contact metallization was employed to study its effect in improving the diode parameters. The KOH-treated diode demonstrated a breakdown voltage of -27.5 V, which is the highest reported for this type of diodes. Cut-off frequencies around 500 GHz were obtained at high reverse bias (-25 V) in spite of high series resistance. The result obtained in breakdown voltage value warrants further research in surface treatment and post-annealing of the Schottky contact optimization in order to decrease the series resistance.

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Schottky barrier diodes (SBDs) with realistic geometries have been studied by means of a 2-D ensemble Monte Carlo simulator. The non-linearity of the Capacitance-Voltage (C-V) characteristic is the most important parameter for optimizing SBDs as frequency multipliers. In this paper, by changing the values of several technological parameters, we analyze their influence on the edge fringing capacitance in a GaN SBD. We have found that the parameters related with the dielectric used for the passivation and the lateral extension of the epilayer significantly affect the fringing capacitance, thus increasing the value of the total capacitance above the ideal one.