High quality In 0.3Ga 0.7As and In 0.51Ga 0.49As epilayers have been successfully grown on the GaAs substrate by MOCVD. A cross-sectional study by transmission electron microscopy showed that the threading dislocations (TDs) have been successfully contained and limited within the buffer layers designed to stop the elongation of TDs into the In 0.3Ga 0.7As and In 0.51Ga 0.49As epilayers. ATD density of 1 × 10 6cm -2 in a fully relaxed In 0.51Ga 0.49As epilayer was achieved. The measurement of lifetimes of n- and p-type In 0.51Ga 0.49As has been done by using time-resolved photoluminescence. A great reduction in the number of recombination centers in the InGaAs epilayer has been shown.