Dislocation density reduction through annihilation in lattice-mismatched semiconductors grown by molecular-beam epitaxy

Abstract
Epitaxial InAs/GaAs, GaAs/Ge/Si, GaAs/InP, and InAs/InP heterostructures are grown by molecular‐beam epitaxy. Transmission electron microscopy studies reveal that, for these heteroepitaxial systems, the threading dislocation density is inversely proportional to the epilayer thickness. At a given thickness, the threading dislocation density is relatively insensitive to lattice mismatch (3.2%<‖Δa‖/a7<‖Δα‖−6 K−1), to interfacial surface chemistry, and to epilayer morphology. Epitaxial layers incorporating growth interrupts produce lower overall defect densities, yet they maintain defect‐reduction profiles similar to those observed in layers without the growth interrupt.