The growth and characterization of GaInAs/AlInAs triple quantum well structures are reported. The structures are characterized with high-resolution X-ray diffraction combined with high-resolution simulation based on the dynamical theory of X-ray diffraction and with photoluminescence. The good agreement in both peak position and intensity of the high-resolution X-ray diffraction spectra with the high-resolution simulation reveals the precise control of the epilayer thickness and the good quality of interfaces. The photoluminescence spectra are analyzed concerning the peak position, interface roughness, and lineshape. These three aspects correlate well with each other, and the interface roughness is determined by fluctuations of 1 monolayer occurring every 3 effective exciton radii in the lateral plane.