Temperature dependent study of InAlAs–InP∕GaAsSb∕InP double heterojunction bipolar transistors

Abstract

In Al As – In P ∕ Ga As Sb ∕ In P double heterojunction bipolar transistors (HBTs) with InAlAs–InP composite emitter have been grown, fabricated, and characterized at various temperatures from 77to400K. The InAlAs–InP composite emitter structure effectively reduces electron pileup in the InP∕GaAsSb base-emitter junction and hence increases current gain, especially in the low-base-current region. The turn-on voltage shows a slightly different temperature dependence (−1.66mV∕K) from conventional InGaAs based HBTs due to the composite emitter. The activation energy study for the base (0.74eV) and collector currents (0.98eV) indicates the high quality of the base layer and the effect of InAlAs–InP composite emitter.

Characterization of conduction band edge discontinuity for InAlAs/GaAsSb using InP/GaAsSb heterojunction bipolar transistors

“…3. The activation energies can thus be determined based on the current at equilibrium versus 1/ T plots 15, 16. For the device under reverse active mode, only base current at V B = 0 is plotted for the extraction of E a .…”

Effect of emitter-base spacer design on the performance of InP/GaAsSb/InP DHBTs grown by MOCVD

“…The current gain of DHBTs has increased due to improved interface quality and reduced conduction band discontinuity ΔEc at the E-B junction. Another method to eliminate the ΔEc is to use a compositionally graded wide-band-gap layer or to insert a strained spacer layer between InP emitter and GaAsSb base such as GaInP [2,5,12,13], InAlP [6], InAlAs [7,14]. Using this structure, the current gain is improved by eliminating the electron pile-up and suppressing the carrier recombination at the E-B junction.…”