Changes of composition profiles in GaInAs layers sandwiched by InP, due to the layer thicknesses, were measured by the x-ray CTR scattering and cross-sectional STM techniques. Both techniques showed quite similar results, which indicates that the x-ray CTR scattering measurements and analyses give us correct composition profiles both for group-III and group-V atoms in the buried heterostructures non-destructively. Limits of the CTR analysis are discussed, especially on the spatial resolution and composition grading below the bottom interface.