High-Speed InP/InGaAsSb DHBT on High-Thermal-Conductivity SiC Substrate

InP/InGaAsSb double heterojunction bipolar transistors (DHBTs) with an Au subcollector were fabricated on a SiC substrate by using a wafer bonding technique. The thermal resistance (R-th) of a fabricated DHBT with a 0.35 x 8.0 mu m emitter is 62% lower than that of a DHBT with the same epitaxial layer structure on an InP substrate. Thanks to the lower R-th, the DHBT operates at a collector current density (J(C)) of over 25mA/mu m(2) without any lowering of current gain. The DHBT exhibits a record f(t) of 695 GHz at J(C) of 21 mA/mu m(2) owing to the reduced emitter charging time by suppressing the Kirk effect.