Compositional grading at hetero-interfaces in InP/GaInAs/InP structures grown by OMVPE at 590, 620, and 650degC with different growth interruption times in TBAs atmosphere were investigated utilizing X-ray crystal truncation rod scattering method. From the analysis of the X-ray CTR scattering spectra, it was shown that the lifetime of As on GaInAs surface was shorter and the As adsorption rate was higher when the growth temperature was higher. The accumulation of As changed sensitively with the change of the growth temperature via the balance of the adsorption and desorption rate of As.