Published online by Cambridge University Press: 28 February 2011
We compare the dynamic responses of reflection high energy electron diffraction (RHEED) and optical reflectance-difference (RD) signals caused by abrupt changes in incident fluences of Ga and As during MBE growth of GaAs on (001) GaAs. Our results reveal that RHEED and RD originate mainly, although not completely, from structural order and chemical bonding, respectively, and thus provide complementary information for real-time studies of MBE growth. We also measure the wavelength dependence of the RD spectrum and show that it can be described approximately from 2 to 4 eV by a single Lorentzian absorption line centered at 2.4 eV.