Strain relaxation in InAs/GaAs(111)A heteroepitaxy

We have studied strain-relaxation processes in InAs heteroepitaxy on GaAs(lll)A using rocking-curve analysis of reflection high-energy electron diffraction. Strain relaxation in the direction parallel to the surface occurs at similar to 1.5 bilayers (BL) thickness. On the other hand, the lattice constant in the direction normal to the surface remains almost unchanged below similar to 3 BL thickness and is estimated to be similar to 3.3 Angstrom. This value, slightly larger than that of bulk GaAs (3.26 Angstrom), does not quite reach the value predicted by classical elastic theory, 3.64 Angstrom. The present result has been supported by the first-principles total-energy calculations.