Current-voltage characteristics of p-InGaN∕n-GaN vertical conducting diodes on n+-SiC substrates

Abstract

p - In Ga N ∕ n - Ga N 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 100A∕cm2 with an on-state resistance of ∼1.3mΩcm2. 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 1.51mΩcm2, leading to the figure-of-merit, (VB)2∕Ron, of 62MW∕cm2.