Interfacial defects and morphology of InGaAs epitaxial layers grown on tilted GaAs substrates

Abstract
Systematic transmission electron microscopy studies of In0.2Ga0.8As layers grown by molecular-beam epitaxy on [001] GaAs substrates and on substrates tilted up to 10° toward [110], [120], [100], [1̄10], and [1̄20] are described. Three different layer thicknesses were investigated: 6, 20, and 40 nm. In the 40 nm layers misfit dislocations were formed which partially relaxed the elastic strain. Three-dimensional growth with an indication of microscale In segregation (dendritic growth) occurred for substrates tilted toward [1̄10] and [1̄20] directions. Smooth growth surfaces were observed when the substrates were tilted toward [110] and [120] showing that the chemistry of the predominant surface growth steps can play an important role in the growth mode and quality of the epitaxial layer. Indium segregation to misfit dislocation cores, the presence of In-rich platelets near the interface, and diffuseness of the interface are considered as evidence for short range migration of In during and after growth.

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