In this work we study the influence of the composition (strain) and the layer thickness of InGaAs grown on (111)B GaAs substrates on the surface morphology and defect distribution (strain relief). Samples of uniform (x = 0.13 or 0.22) and graded (x(initial) = 0.10 for each sample; x(final) = 0.17 and 0.25) composition have been studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The relaxation mechanism for the two series of samples is the same. SEM observations reveal a surface roughness with a triangular structure, where the 'cross-hatch pattern' distribution is more isotropic and homogeneous as the thickness and In composition increase. Misfit dislocations and deformation twins (band twins), anisotropically and inhomogeneously arranged, are observed in all the studied samples. Deformation twins are formed by the nucleation of partial dislocations from the film surface. A mechanism of the observed band twins formation is proposed.