Optical and structural properties of tensile strained graded GaxIn1-x buffers grown on GaAs substrate have been studied by photoluminescence, X-ray diffraction, atomic force microscopy, and scanning electron microscopy measurements. The Ga composition in the graded buffer layers was varied from x=0.51 (lattice matched to GaAs) to x=0.66 (1% lattice mismatch to GaAs). The optimal growth temperature for the graded buffer layer was found to be about 80-100 degrees C lower than that for the lattice matched GaInP growth. The photoluminescence intensity and surface smoothness of the Ga0.66In0.34P layer grown on top of the graded buffer were strongly enhanced by temperature optimization. The relaxation of tensile GaInP was found to be highly anisotropic. A 1.5 mu m thick graded buffer led to a 92% average relaxation and a room temperature photoluminescence peak wavelength of 596 nm. (C) 2010 Elsevier B.V. All rights reserved.