High-power characteristics of GaN/InGaN double heterojunction bipolar transistors

Abstract

High-power characteristics have been investigated for GaN/InGaN double heterojunction bipolar transistors (HBTs) on SiC substrates. A base-collector diode showed a high breakdown voltage exceeding 50 V, which is ascribed to a wide band gap of a GaN collector. The maximum collector current is proportional to the emitter size in the emitter-size ranging from ${\text{1.5×10}}^{\text{−5}}$ to ${\text{1.4×10}}^{\text{−4}}\hspace{0.17em}{\mathrm{cm}}^2.$ The corresponding maximum collector current density is as high as $\text{6.7\hspace{0.17em}}{\mathrm{kA/cm}}^2,$ indicating the high current density characteristics of bipolar transistors. A 50 μm×30 μm device operated up to a collector–emitter voltage of 50 V and a collector current of 80 mA in its common-emitter current–voltage characteristics at room temperature. The corresponding power density is as high as $\text{270\hspace{0.17em}}{\mathrm{kW/cm}}^2,$ showing that nitride HBTs are promising for high-power electronic devices in terms of both the material and the device structure.