Control of plasticity with coherency strain

We report measurements of the mechanical properties by nanoindentation at room temperature on coherently strained superlattices of InxGa1-xAs grown on InP. Elastic deformation and then plastic deformation are obtained. The yield pressure decreases with increasing strain modulation in the superlattice and, at the highest strains of 0.8%, the yield pressure is halved. In the plastic regime the behaviour again depends on the strain modulation. These results demonstrate the potential of tailoring coherency strain between layers in thin films to control their mechanical properties.