The influence of localization and disorder in (GaIn)As/(AlIn)As heterostructures with spatially separated photoconductive and recombination regions designed as a material for THz antennas for telecom applications at 1.55μm is investigated by photoluminescence spectroscopy. The emission is studied as a function of lattice temperature for a series of samples with different growth temperatures. Strain-induced disorder is identified as the main contribution to carrier localization. In addition, inhomogeneous broadening as well as PL intensity is strongly influenced by the impurity density in the barrier material. The optimal configuration as THz antenna material is achieved at a growth temperature of 375 °C.