Effect of InAlAs emitter on the microwave performance of InAlAs/InGaAs abrupt npn heterojunction bipolar transistor

Saied Tadayon; Bijan Tadayon; Lester Fuess Eastman

doi:10.1117/12.20909

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1 August 1990 Effect of InAlAs emitter on the microwave performance of InAlAs/InGaAs abrupt npn heterojunction bipolar transistor

Saied Tadayon, Bijan Tadayon, Lester Fuess Eastman

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Proceedings Volume 1288, High-Speed Electronics and Device Scaling; (1990) https://doi.org/10.1117/12.20909
Event: Advances in Semiconductors and Superconductors: Physics Toward Devices Applications, 1990, San Diego, CA, United States

Abstract

Npn InAIAs/InGaAs abrupt heterojunction bipolar transistor (HBT) structures were grown on InP substrates, by the molecular beam epitaxy (MBE). Transistors were fabricated by using a non-self-aligned technology which uses a selective wet etching to reach the base layer. DC measurement showed that the base current was dominated by the depletion region recombination in the base-emitter junction. CV measurement showed a lot of defects in the heavily compensated InAIAs emitter. The collector current densities for the different layers correlated with the CV measurement results. The microwave measurements on the 4 ?m x 5 ?m emitter InAIAs /InGaAs HBT resulted in ft and fmax of 47 GHz and 27 GHz, respectively. The bias scan and the S-parameter measurement showed that the microwave performance of the device was limited by the parasitic resistance in the emitter, which was much bigger than the emitter contact resistance. This extra emitter resistance was due to the undepleted and heavily compensated InAIAs emitter. A physical small signal circuit model showed that in the absence of this extra emitter resistance, f{ would become more than 70 GHz. A much better performance is expected with a higher InAIAs emitter dopings, such as 1x1018 cm-3, which reduces the extra parasitic resistance in the InAIAs emitter significantly.

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Saied Tadayon, Bijan Tadayon, and Lester Fuess Eastman "Effect of InAlAs emitter on the microwave performance of InAlAs/InGaAs abrupt npn heterojunction bipolar transistor", Proc. SPIE 1288, High-Speed Electronics and Device Scaling, (1 August 1990); https://doi.org/10.1117/12.20909

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