Fabrication of InP‐based NnpnN heterojunction bipolar transistor

InGaAs(P)/InP double heterojunction bipolar transistors have been successfully fabricated by inserting an n‐type InGaAsP (Eg=0.95 eV) quaternary (0.1 μm, undoped) layer on either side of the base by liquid‐phase epitaxy (LPE). As we know, it is the first time to grow this structure by LPE. These devices have been fabricated using a non‐self‐aligned technology. In this case it can improve the common‐emitter current/voltage (IC /VCE) characteristics. Small signal current gain hfe about 100 and dc current gain hFE about 80 at IC=38 mA can be obtained. The ideality factor of emitter‐base junction is 1.43.