It is demonstrated by using reflection high-energy electron diffraction and transmission electron microscopy that the epitaxial growth of highly strained InxGa1-xAs (x>0.3) layers on GaAs(001) is improved by a preadsorbed Te surfactant layer. The formation of 3D islands is inhibited by the surfactant action and consequently the onset of plastic relaxation (i.e., the critical thickness) is significantly delayed.