Characterization of InAlAs/In0.25Ga0.75As0.72Sb0.28/InGaAs double heterojunction bipolar transistors

We report on the characterization of InP-based heterojunction bipolar transistors (HBTs) with low turn-on voltage and high current gain by using InGaAsSb as the base layer. The low turn-on voltage of 0.43 V is attributed to the smaller band gap of the In
_0.25
Ga
_0.75
As
₀₇₂
Sb
_0.28
material. High current gain of 74 is observed despite a heavily Be-doped (9.0×10
¹⁹
cm
^-3
) base is used, suggesting a long minority carrier lifetime (τ
_n
) in the InGaAsSb material. Moreover, low specific contact resistivity of 5×10
^-8
Ω-cm
²
is also demonstrated on separate In
_0.25
Ga
_0.75
As
₀₇₂
Sb
_0.28
samples.