We explore the optimum growth space for a 47.0A ° InAs/21.5A ° Ga0.75In0.25Sb superlattices (SLs) designed for the maximum Auger suppression for a very long wavelength infrared gap. Our growth process produces a consistent gap of 5065meV. However, SL quality is sensitive to the growth temperature (Tg). For the SLs grown at 390 470 C, a photoresponse signal gradually increases as Tg increases from 400 to 440 C. Outside this temperature window, the SL quality deteriorates very rapidly. All SLs were n-type with mobility of 10 000 V/cm2 and 300K recombination lifetime of 70 ns for an optimized SL