In0.2Ga0.8As/GaAs strained layer superlattices were grown by molecular‐beam epitaxy with various GaAs barrier thicknesses to study how this affects the properties of nominally 90‐A˚‐thick InGaAs wells. Double‐crystal x‐ray diffraction, photoconductivity, and photoluminescence gave similar results regarding superlattice degradation with decreasing barrier thickness. The optical measurements showed that at 58‐A˚‐GaAs thickness, the strained layer superlattice was relaxed with concomitant deterioration of its optical properties.