The structural analysis of thin InxGa1-xAs layers grown by molecular beam epitaxy on (001) oriented InP substrates in the range of tensile deformation (x<0.53) was performed by means of atomic force and transmission electron microscopies. The evolution of the surface from planar to faceted is described, together with a complete characterization of the defects nucleated during growth. The observed anisotropy on defect formation is proposed as being directly related to the anisotropy on the rough surface morphology.