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

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 nonun iformly distributed at the interface of the substrate and the epilayer and a particular kind of phase whose In concentration is about 0.02 e xists at the interface. The tensile stress due to the dislocation rema ins up to 5 mu m thickness. The magnitude of the residual tensile stra in is about 2/3 times that of the compressive strain due to the lattic e mismatch. And from the Raman scattering study we observed that Raman shifts by the strain are slightly larger than those by the alloying e ffect for 0<x<0.2. The frequency changes of the LO and the TO phonon m odes caused by the strain are about 27.0x and -13.6x, respectively.