We report an investigation of the effects of interface layer composition on the structural and electronic properties of Ga1−xInxSb/InAs superlattices, which are of interest for infrared detector applications. Shutter sequencing during growth of a series of Ga0.75In0.25Sb (8 ML)/InAs (13 ML) superlattices by molecular‐beam epitaxy has been employed to select structures with GaInAs‐like interfaces, InSb‐like interfaces, and intermediate choices of interfacial composition. Comparison of x‐ray diffraction scans from the superlattices confirms that a superlattice with GaInAs‐like interfaces has a 1.6% smaller average interatomic spacing in the growth direction than a sample with InSb‐like interfaces, in near agreement with expected interfacial bond length differences. Hall measurements of intrinsic carrier concentrations at high temperatures indicate an increase in superlattice energy gap when interfaces are switched from InSb‐like to GaInAs‐like, consistent with intuitive expectations. Low temperature Hall me...