Indium phosphide on silicon heteroepitaxy: Lattice deformation and strain relaxation

Lattice deformation and strain relaxation in epitaxial InP directly on (001) Si are studied as a function of layer thickness using x-ray diffraction and photoluminescence (PL) techniques. The heteroepilayers were grown by low-pressure organometallic vapor-phase epitaxy and showed good quality. We find that mismatch-induced compressive strains are still present in InP layers with a thickness less than 1 μm. The rate of strain release is much lower than the prediction based on the equilibrium theory. With increasing thickness above 1.1 μm, the InP/Si layers suffer in-plane tensile strains as a result of differential thermal contraction during the cooling process after growth. Fairly good agreement is found between the PL and x-ray data for the strain variations in the InP/Si heterostructures.