Current gain enhancement in GaAsSb/InP - DHBT type grown by MBE with a graded composition AlInP emitter

Al
_x
In
_1-X
P/GaAs
_0.51
Sb
_0.49
DHBTs with various aluminum contents have been grown by MBE. This was motivated by the poor current gain of the InP/GaAsSb structure. From x = 0.00 to 0.30 the best result is obtained with x = 0.25 with a current gain around 6 times higher.