Strain-induced surface morphology of slightly mismatched InxGa1−xAs films grown on vicinal (100) InP substrates

Abstract

A surface investigation by atomic force microscope of InP and slightly lattice-mismatched InGaAs epilayers grown by metalorganic vapor phase epitaxy shows the effect of strain on InGaAs/InP surface morphology. Epilayers were grown at 600 °C with arsine at 760 Torr. We could clearly observe the regular step/terrace-like feature of the vicinal surface morphology for InP and InGaAs lattice-matched epilayers. It is shown that the step flow mode appears with a step edge with regular spacing for lattice-matched epilayers. A crosshatch pattern, i.e., an array of perpendicular lines visible at the surface, were obtained for strain-relaxed InGaAs epilayers (|(Δa/a)⊥|>10−3) with an average separation of 1000–1500 nm. The detailed surface structure of the step edge presents a specific bending of terraces. The influence of step kinetics on the morphological stability of the surface will be illustrated. The relationship between the misfit dislocation network and anisotropic growth rate of the front step will be discussed.