Stacking fault pyramids, island growth and misfit dislocations in InxGa1-xAs/InP heterostructures grown by vapour phase epitaxy

Intentionally mismatched InxGa1-xAs/InP layers (0.49 <= x <= 0.74) were grown to study the relationship between layer composition and layer defects. The threading dislocations were present in quite a high density for x >=0.53 but absent for lower indium concentrations. The stacking fault pyramids had the opposite behaviour with a density maximum at x = 0.49. They almost disappeared for x>= 0.63. Such a dependence on x together with the high resolution transmission electron microscopy detection of irregularities in the first atomic layers in the InxGa1-xAs films when x < 0.53 might suggest that the stacking fault pyramids are generated at interface imperfections related to gallium excess. The absence of any cross-grid pattern of misfit dislocations would indicate that the growth is dominated by island growth especially for x> 0.53. The threading dislocations very probably originated from the misfit dislocations generated at the growth islands.