Bipolar III-N high-power electronic devices

Abstract

We report high performance GaN-based npn heterojunction bipolar transistors (HBTs) grown by metalorganic chemical vapor deposition (MOCVD) with state-of-the-art high collector current density (JC) and low knee voltage (Vknee). For HBTs grown on sapphire, the common-emitter I-V characteristics show high JC > 16 kA/cm2 with an offset voltage (Voffset) of <; 0.25V, Vknee <; 2.4 V and BVCEO = 105 V. High-temperature performance is also evaluated for InGaN HBTs grown on a free-standing GaN substrate. The device shows the peak current gain reduces from 93 at 25 C to 35 at 250C. Higher free hole concentration in the p-InGaN base is observed at elevated temperature that helps reduce the base resistance and Vknee in high-temperature InGaN HBTs operation.