Oscillations in the optical response of (001)GaAs and AlGaAs surfaces during crystal growth by molecular beam epitaxy

Upon initiation of growth by molecular beam epitaxy, reflectance‐difference (RD) signals for (001)GaAs and AlAs surfaces exhibit a cyclic component that is periodic with (001) atomic bilayer coverage and that follows either surface structure or surface chemistry (coverage), depending on measurement wavelength. These RD oscillations may be phase shifted with respect to their reflection high‐energy electron diffraction counterparts, depending on deposition conditions.