Summary: Experimental I▒V characteristics of AlGaAs/GaAs and
GaInP/GaAs (D)HBTs with thin bases
*, P.M. Asbeckb
Department of Electrical Engineering, National Central University, Chung-Li, 320, Taiwan
Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093-0407, USA
Received 25 January 1999; received in revised form 20 October 1999
N▒p▒n AlGaAs/GaAs and GaInP/GaAs (double) heterojunction bipolar transistors with thin base widths down
to 200 A╩ have been fabricated, and their collector and base current▒voltage characteristics have been studied. The
experimental results show that the surface recombination current and the base bulk recombination current are lower
in 200 A╩ base AlGaAs/GaAs HBTs than in comparable devices with 500 A╩ base width. The experiment also showed
that the surface recombination currents and the sum of other base recombination currents (the base bulk
recombination current, the base-emitter junction space charge recombination current, and the base-to-emitter back-
injected current) are signi«cantly lower in GaInP/GaAs (D)HBTs than that in comparable AlGaAs/GaAs HBTs.
For the thin base GaInP/GaAs (D)HBTs, the current gain measurements with dierent emitter sizes demonstrates
high current gain, low emitter edge recombination and negligible emitter-size eect. 7 2000 Elsevier Science Ltd.
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