Surface morphology effects on the optical phonon modes in InAsxSb1–x epilayers on GaAs(001)

We have studied Raman scattering from longitudinal- and transverse-optical (LO and TO) phonon modes in InAsxSb1–x epilayers grown on GaAs(001) substrates with various arsenic compositions (x). InSb-like and InAs-like LO and TO phonon modes of the epilayers are observed. We find that the peak intensity ratio of the InAs-like LO to TO-mode decreases for x 0.6. This intensity ratio change is attributed to two- and three-dimensional (2D and 3D) growth mode of the epilayers using atomic force microscopy. Further, the intensity ratio depends on the root mean square surface roughness of the alloy. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)