This study focuses on GaN heterostructure Schottky diodes with different geometries, aiming at achieving high breakdown voltage and high forward current. The AlGaN/GaN heterostrure devices are attractive due to their high mobility and high carrier density of two-dimensional electron gas at the AlGaN/GaN interface, which allows low on-state resistance of the devices. In this thesis, we design and fabricate the GaN Schottky diodes to have high forward current, high breakdown voltage, and low reverse recovery time. In GaN Schottky diodes with a buffer layer thickness of 2.4 μm, the measured breakdown voltage is higher than 900 V. The GaN diodes with a large area are also investigated to obtain a large output current. We propose of using vertical pads above the active region, which greatly increases the efficiency of area usage. We also design the circle-type testkeys to ensure the feasibility of the proposed ideas. The large-area AlGaN/GaN Schottky diode with a total size of 0.57 shows a forward current 1A (corresponding to a current density of ~ 0.18A/mm2) at an applied forward voltage of 2V after wire bonding. In reverse recovery tests, the GaN diode shows a very short switching time (trr) of only 21 ns.

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