Optical Characterization of GaAs/Si Layers Grown by the Conformal Method (Confined Lateral Epitaxial Growth)

Abstract

Optical studies of conformal GaAs layers grown on silicon substrates were carried out by cathodoluminescence, photoluminescence imaging, and micro-Raman spectroscopy. These techniques revealed, in the conformal GaAs layers, local variations of the luminescence intensity with the shape of stripes both parallel and perpendicular to the GaAs seed, associated with local variations of tensile stress. The cathodoluminescence and micro-Raman spectra suggest that this distribution of tensile stress plays an important role in the formation of mid-gap states responsible for the variations of the luminescence intensity. The high luminescence emission of the conformal GaAs layers compared to the emission of the GaAs seed grown directly on the Si substrate is consistent with the high quality of the conformal layers.