Surface Leakage in GaN/InGaN Double Heterojunction Bipolar Transistors

Abstract
We report a study on the surface-leakage current in GaN/InGaN double heterojunction bipolar transistors (DHBTs) that are grown on a sapphire substrate. Surface-leakage-current densities on an unpassivated DHBT are 9.6 times 10-5 - 5.8 times 10-4 A/cm for JC = 0.5-50 A/cm2. A fabricated n-p-n GaN/InGaN DHBT shows the common-emitter dc current gain of 42, the collector-current density of 5.2 kA/cm2, and the common-emitter breakdown voltage (BVCEO) of 75 V.