RAMAN-SCATTERING STUDY OF INGAASP QUATERNARY ALLOYS GROWN ON INP IN THE IMMISCIBLE REGION

We have studied the asymmetric broadening of the Raman spectra of InxG a1-xAsyP1-y grown on InP in the immiscible region using the spatial co rrelation model. The compositional dependence of Raman peaks are well explained by a simple model which does not account for the immiscibili ty. However, the broadening of the Raman line shape is greatly enhance d in the samples in the region of the immiscibility. In particular, th e asymmetry of the spectral peak of the InAs-like longitudinal optical phonon is found to be enhanced in the immiscible region. This shows t hat the samples which include the immiscibility have been structurally changed to suppress the uniform distribution of the long wavelength p honons.