p-InGaN/n-GaN vertical conducting diodes have been grown on n+-SiC substrates by low-pressure metalorganic vapor phase epitaxy and their current-voltage characteristics have been investigated. The typical forward voltage drop was 3.8–4.0 V at a forward current density of 100 A/cm2 with an on-state resistance of ∼1.3 mΩ cm2. The ideality factor of the samples was ∼2, meaning that the tunneling current through defects is small enough in these devices. The breakdown voltage (VB) increased with increasing n-GaN layer thickness, while it increased with decreasing carrier concentration of the layer by substituting undoped GaN for n-GaN. When the undoped GaN layer thickness was increased to 1800 nm, the highest breakdown voltage of 305 V was obtained with a low on-state resistance (Ron) of 1.51 mΩ cm2, leading to the figure-of-merit, (VB)2/Ron, of 62 MW/cm2.