Weak emitter-size effect in InP/In0.37Ga0.63As0.89Sb0.11/In0.53Ga0.47As double heterojunction bipolar transistors

This study shows that the current gain of InGaAsSb base DHBTs is less sensitive to the emitter size and collector current density (J
C
) due to their low surface recombination. The deduced emitter periphery surface recombination current (K
B,surf
) of type-I InP/In
0.37
Ga
0.63
As
0.89
Sb
0.11
HBTs is 1.57×10
⁻⁵
µA/μm at J
C
= 0.1 A/cm
²
, which is twenty times lower than that of the conventional InP/InGaAs SHBTs. The results manifest the great potential of InGaAsSb base for aggressively scaled THz HBTs.