“…1,2) In particular, a GaAs 1Àx Sb x (x ¼ 0:49) epilayer lattice-matched to a InP substrate is attractive for application in 1.6 mm infrared devices. 3,4) From the viewpoint of the wider applications of GaAsSb semiconductors, GaAsSb layers grown on GaAs substrates can be applied in data-communication lasers in the 1.3-1.5 mm wavelength range, 5) as well as in heterojunction bipolar transistors (HBT) with a GaAsSb base region. 6,7) In general, in III-V A V B -type alloyed crystals like GaAs 1Àx Sb x , the compositional control of V A and V B is more difficult than it is in III A III B -V-type alloys; therefore, the control of the doping of III-V A -V B alloys is much more difficult.…”