TRANSITION FROM ISLAND TO CONTINUOUS INP LAYER GROWTH ON (001)GAAS BY MOCVD

Low pressure metal-organic chemical vapour deposition grown InP/GaAs layers were analysed using scanning and transmission electron microscopy and Rutherford backscattering spectroscopy to characterize the evolution of the InP layer morphology from the initial stages of the growth up to the complete substrate coverage. Up to nominal thicknesses of about 100-150 nm, an appreciable fraction of the GaAs substrate is not covered by InP. For higher thicknesses, a sudden transition to an enhanced lateral growth leading to island coalescence was observed. Finally, a third growth stage leads to the complete filling of the valleys, leading to continuous layers. The results are discussed in terms of the phenomenological models proposed in the literature.