Transmission electron microscope and transmission electron diffraction observations of alloy clustering in liquid-phase epitaxial (001) GaInAsP layers

Transmission electron microscope examinations performed on liquid-phase epitaxial GaInAsP layers grown on (001) InP substrates showed a coarse tweed structure (∼150-nm scale) and a fine granular structure (∼15-nm scale). Transmission electron diffraction patterns revealed main spots with associated satellite spots, indicating the presence of periodic variations in lattice parameter along the [100] and [010] directions and of wavelength corresponding to the fine granular structure. The particular behavior depended on the alloy layer composition. Both structures are attributed to alloy clustering arising from spinodal decomposition.