REPRESENTATIVE REFLECTANCE ANISOTROPY SPECTRA FROM AL(X)GA(1-X)AS LAYERS (X=0 TO 1.0) GROWN ON GAAS(001) BY MOLECULAR BEAM EPITAXY

We present in this study reflectance anisotropy spectra also termed reflectance difference spectra for the surfaces of thick Al(x)Ga(1−x)As (x=0.0, 0.25, 0.50, 0.75, 1.00) layers grown on GaAs(001) by molecular beam epitaxy (MBE). Layers ≥2 μm thick were grown in order to minimize the interference effects from the buried interface and to obtain spectra representative of bulk Al(x)Ga(1−x)As surfaces. All surfaces were also independently characterized using reflection high energy electron diffraction (RHEED), and found to exhibit a c(4×4) reconstruction. The reflectance anisotropy spectra were qualitatively similar to one another, but showed clear dependence of energy and magnitude upon the mole fraction x. These spectra can serve as reference for determining stochiometries in MBE growth of Al(x)Ga(1−x)As and probably should be useful for future comparison to metalorganic vapor phase epitaxy (MOVPE) Al(x)Ga(1−x)As growth.