STEP-BUNCHING IN (ALXGA1-X)(0.5)IN0.5P LAYERS ON MISORIENTED (001)GAAS SUBSTRATES GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

Step-bunching in metalorganic vapor phase epitaxy (MOVPE) growth for G a0.5In0.5P and (Al0.6Ga0.4)(0.5)In0.5P was studied. Crystals were grow n at 660 degrees C, at V/III ratios of 55 and 1500. Vicinal (001) subs trates were used. When GaInP was grown on (001) GaAs misoriented by 6 degrees in the [110] and in the [110] directions at V/III = 55, step-b unching was significant. When V/III was increased to 1500, however, st ep-bunching was largely suppressed. On the other hand, step-bunching f or AlGaInP was fairly well suppressed even at low V/III of 55. Composi tional modulation occurred in the AlGaInP layer, which is identified a s the In/Ga-deficient and In/Ga-rich areas. The In/Ga-rich areas coinc ide with the traces of the bunched surface during growth.