Optical Investigation on the Growth Process of GaAs during Migration-Enhanced Epitaxy

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Abstract
The growth process of GaAs is investigated using optical reflection during migration-enhanced epitaxy which is based on an alternate deposition of Ga atoms and As4 molecules onto the growing surface. A linearly polarized laser light is irradiated at a 20° angle with respect to the (001)-oriented GaAs substrate surface. A 325-nm He-Cd laser light with polarization E vector perpendicular to the substrate surface is more efficiently reflected from Ga-stabilized surfaces than from As-stabilized surfaces. Thus, strong and persistent oscillation in reflection intensity is observed during the alternate deposition of Ga and As4. When the polarization E vector of the incident light is parallel to the growing surface, no oscillation is observed. These results imply that the observed optical reflection oscillation is related to the optical absorptions caused by an electronic transition in the As-stabilized surface which couples efficiently with light whose polarization vector is normal to the surface.