Coherency strain as an athermal strengthening mechanism

We have grown homogeneous thick layers of InGaAs on InP with 0.2% strain and also coherently strained superlattices with the same net strain. The thick layers can relax by plastic deformation during growth, and relax further under annealing at higher temperatures. In contrast, superlattices with alternating coherency strains remain fully strained even under annealing at 900 degrees C, above 85% of their estimated melting points. We conclude that coherency strain can be a powerful strengthening mechanism which is athermal and hence useful for high-temperature structural materials.