High-speed performance of NpN InGaAsN-based double heterojunction bipolar transistors

We report the fabrication of double heterojunction bipolar transistors (DHBTs) with the use of a new quaternary InGaAsN material system that takes advantage of a low energy band gap in the base to reduce operating voltages in GaAs-based electronic devices. InGaP/In/sub 0.03/Ga/sub 0.97/As/sub 0.99/N/sub 0.01//GaAs DHBTs with improved band gap engineering at both heterojunctions exhibit a DC peak current gain over 16 with small active emitter area. The use of the InGaAsN base layer allows a significant reduction of the turn-on voltage by 250 mV for the new technology over a standard InGaP/GaAs HBT, while maintaining high-frequency characteristics with cut-off frequency and maximum oscillation frequency as high as 40 GHz and 70 GHz, respectively. This technology is promising for next generation RF circuits using GaAs-based HBTs by reducing the operating voltage for low power consumption and better handling of supply voltages in advanced wireless handsets.