$\hbox{In}_{0.46}\hbox{Ga}_{0.54}\hbox{P}_{0.98} \hbox{Sb}_{0.02}/\hbox{GaAs}$: Its Band Offset and Application to Heterojunction Bipolar Transistor

We report on the band alignment of In
_0.46
Ga
_0.54
P
_0.98
Sb
_0.02
/GaAs and the dc characteristics of In
_0.46
Ga
_0.54
P
_0.98
Sb
_0.02
/GaAs heterojunction bipolar transistors (HBTs). By comparing the forward and reverse Gummel plot, we found a potential spike existing at the InGaPSb/GaAs interface. Through a flatband extrapolation from the currents of the forward and reverse Gummel plot and the energy gap determined from photoluminescence, we concluded that In
_0.46
Ga
_0.54
P
_0.98
Sb
_0.02
/GaAs is in a type-I band alignment. The conduction-band offset and valence-band offset are 0.12 and 0.35 eV, respectively. As a result of the type-I band alignment, the InGaPSb/GaAs HBTs showed a more significant thermal degradation of the current gain than the control InGaP/GaAs HBT. The thermal behavior is beneficial to ruggedness.