Raman scattering from InxGa1−xAs grown on GaAs(001) by molecular beam epitaxy

We have performed room temperature Raman scattering measurements, in a backscattering configuration X(YZ), for InxGa1−xAs grown on GaAs(001) by molecular beam epitaxy. The position of the “GaAs-like” longitudinal optical (LO) phonon mode is seen to move toward lower wavenumber in a continuous manner with increasing indium concentration. By calibrating the peak position of this LO phonon against the indium mole fraction, as determined from double crystal X-ray diffraction measurements, we emphasize the use of Raman scattering to measure InxGa1−xAs composition. In addition, we have carried out a study of InAs and In0.56Ga0.44As, grown on GaAs(001), as a function of growth temperature. The InAs LO phonon peak becomes asymmetrical, towards lower wavenumber, with decreasing growth temperature. A second feature, indicative of increasing disorder in the InAs epilayer, becomes evident in the Raman spectra for growth temperatures below 330 °C. Little change is observed in the Raman spectra for In0.56Ga044As over a large range of growth temperatures