PHOTOREFLECTANCE AND RAMAN-SCATTERING STUDIES ON INXGA1-XAS/GAAS STRAINED HETEROSTRUCTURE GROWN BY METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION

Abstract

We investigate the photoreflectance and Raman spectra of the thin and thick InxGa1-xAs/GaAs epitaxial heterostructure grown by metal-organic chemical vapor deposition. It is observed that the In atoms are nonuniformly distributed at the interface of the substrate and the epilayer and a particular kind of phase whose In concentration is about 0.02 exists at the interface. The tensile stress due to the dislocation remains up to 5 mu m thickness. The magnitude of the residual tensile strain is about 2/3 times that of the compressive strain due to the lattice mismatch. And from the Raman scattering study we observed that Raman shifts by the strain are slightly larger than those by the alloying effect for 0<x<0.2. The frequency changes of the LO and the TO phonon modes caused by the strain are about 27.0x and -13.6x, respectively.