Power performance and reliability of AlInAs/GaInAs/InP double heterojunction bipolar transistors

AlInAs/GaInAs/InP double heterojunction bipolar transistors (DHBT) combine the high-frequency performance advantages of the InP-based HBT technology with the high breakdown and low output conductance advantages of the GaAs-based HBT´s. InP-based DHBT´s reported here are composed of a wide bandgap AlInAs emitter, a GaInAs base, and a wide bandgap InP collector. The two heterojunctions are compositionally graded to smooth out the potential barriers at the heterointerfaces. We have used physical device modeling to analyze the device performance, particularly at high current densities. DHBT´s have high Early voltages and are therefore suitable for analog circuit applications. In this paper we concentrate on the high breakdown property of this device technology for microwave power amplification. We have fabricated and characterized power cells with 240 μm² emitter geometries. We measured power densities as high as 6 W/mm² on power cells biased at 11 V and power added efficiencies of 60% on power cells biased at 10 V for applications at X-band frequencies. For integrated circuit applications, DHBT´s which are epitaxially grown with a gas-source MBE system exhibit stable current gain and turn-on voltage characteristics under bias and temperature stress