Surface Leakage in GaN/InGaN Double Heterojunction Bipolar Transistors

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 are9.6 × 10⁻⁵–5.8 × 10⁻⁴\ A/cmforJC = 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 5.2kA/cm², and the common–emitter breakdown voltage(BVCEO)of 75 V.