Investigation of oval defects in InGaAs/GaAs strained-layer heterostructures using cathodoluminescence and wavelength dispersive spectroscopy

Molecular beam epitaxy (MBE) has been widely used to grow epitaxial films, particularly when precise control over the epitaxial layer thickness or abrupt junctions are required. However, oval defects have been found in MBE-grown lattice-mismatched InGaAs/GaAs heterostructures. These act as a primary source of misfit dislocation generation. As a result, it is essential to understand the nature of these oval defects. In this study, we investigate the nature of oval defects using cathodoluminescence (CL) and wavelength dispersive X-ray spectroscopy (WDS).