Raman scattering in a Ga1− x In x P strained heterostructure

Raman scattering was employed to study the optical phonon modes in Ga1−x Inx P heterostructures. The stress calculated from the pressure coefficient and the observed frequency shift for the GaP-like LO phonon is larger than the one obtained from the lattice mismatch given by the elastic theory; the possibility of other types of defects responsible for this difference is considered. The presence of internal stress in epitaxial layers could induce a switchover from one- to two-mode behavior. The modified random element isodisplacement model is used to explore this possibility.