Lattice Relaxation of Eras/Gaas: An X-Ray Scattering Study

Abstract

The results of a high resolution x-ray scattering study of [001]ErAs epitaxial layers grown on [001]GaAs is presented. ErAs is pseudomorphic on GaAs for thicknesses below 70Å and, for thicker films, lattice relaxation is oberved concomitant with an Increase of the In-plane mosaic due to the formation of misfit dislocations. Above 300Å, the out-of-plane transverse scattering from the ErAs lattice planes Is no longer specular and further relaxation Is related to the out-of-plane mosaic. The ratio of elastic constants, C12/C11, Is determined to be 0.126 and the thermal expansion was measured. Thin film Interference oscillations are observed and modeled. ErAs/GaAs Is an Ideal system for x-ray scattering studies of lattice relaxation and structure in epitaxial layers. Films as thin as 20Å have been studied.