Experimental I-V characteristics of AlGaAs/GaAs and GaInP/GaAs (D)HBTs with thin bases

N-p-n AlGaAs/GaAs and GaInP/GaAs (double) heterojunction bipolar transistor s with thin base widths down to 200 Angstrom have been fabricated, and thei r collector and base current-voltage characteristics have been studied. The experimental results show that the surface recombination current and the b ase bulk recombination current are lower in 200 Angstrom base AlGaAs/GaAs H BTs than in comparable devices with 500 Angstrom base width. The experiment also showed that the surface recombination currents and the sum of other b ase recombination currents (the base bulk recombination current, the base-e mitter junction space charge recombination current, and the base-to-emitter back-injected current) are significantly 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 different emitter sizes demonstrates hig h current gain, low emitter edge recombination and negligible emitter-size effect. (C) 2000 Elsevier Science Ltd. All rights reserved.