Structural characterization of AlGaAs:Si/GaAs (631) heterostructures as a function of As pressure

AlGaAs:Si/GaAs heterostructures were grown on (631) and (100) GaAs substrates and studied as a function of the As cell beam equivalent pressure. High-resolution x-ray diffraction patterns showed that the highest quality AlGaAs epitaxial layers were grown at PAs = 1.9 × 10−5 for (100)- and PAs = 4 × 10−5 mbar for (631)-oriented substrates. Raman spectroscopy revealed higher crystalline quality for films grown on (631) oriented substrates. The GaAs- and AlAs-like modes of the AlGaAs(631) films exhibited increased intensity ratios between the transverse optical phonons and longitudinal optical phonons with increasing PAs, whereas the ratios were decreased for the (100) plane. This is in agreement with the selection rules for (631) and high-resolution x-ray diffraction observations. Anisotropy and surface corrugation of the AlGaAs(631) films also were characterized using atomic force microscopy and Raman spectroscopy.