High-speed InGaP/InGaAsN/GaAs NpN double heterojunction bipolar transistors with low turn-on voltage

Abstract A current gain β of 23 is demonstrated from a small-area NpN GaAs- based double heterojunction bipolar transistor (HBT) using a low band-gap InGaAsN material (lattice matched to GaAs with an energy band gap E G of 1.2 eV) as the base layer. An improved band-gap engineering design at both emitter–base and base–collector heterojunctions in this GaAs-based HBT structure allows significant turn-on voltage reduction up to 270 mV compared to conventional InGaP/GaAs HBTs, while attaining high-speed performance. Self-aligned devices with emitter active area of 3×5 μm 2 show cutoff frequency f T and maximum oscillation frequency f MAX values of 32 and 52 GHz, respectively. These results demonstrate the strong potential of this novel HBT technology to reduce power consumption in future wireless handsets using the GaAs manufacturing platform.