Deformation behavior of coherently strained InAs/GaAs(111) A heteroepitaxial systems: Theoretical calculations and experimental measurements

A comprehensive, quantitative analysis is presented of the deformation beha vior of coherently strained InAs/GaAs(111)A heteroepitaxial systems. The an alysis combines a hierarchical theoretical approach with experimental measu rements. Continuum linear elasticity theory is linked with atomic-scale cal culations of structural relaxation for detailed theoretical studies of defo rmation in systems consisting of InAs thin films on thin GaAs(111)A substra tes that are mechanically unconstrained at their bases. Molecular-beam epit axy is used to grow very thin InAs films on both thick and thin GaAs buffer layers on epi-ready GaAs(111)A substrates. The deformation state of these samples is characterized by x-ray diffraction (XRD). The interplanar distan ces of thin GaAs buffer layers along the [220] and [111] crystallographic d irections obtained from the corresponding XRD spectra indicate clearly that thin buffer layers deform parallel to the InAs/GaAs(111)A interfacial plan e, thus aiding in the accommodation of the strain induced by lattice mismat ch. The experimental measurements are in excellent agreement with the calcu lated lattice interplanar distances and the corresponding strain fields in the thin mechanically unconstrained substrates considered in the theoretica l analysis. Therefore, this work contributes direct evidence in support of our earlier proposal that thin buffer layers in layer-by-layer semiconducto r heteroepitaxy exhibit mechanical behavior similar to that of compliant su bstrates [see, e.g., B. Z. Nosho, L. A. Zepeda-Ruiz, R. I. Pelzel, W. H. We inberg, and D. Maroudas, Appl. Phys. Lett. 75, 829 (1999)]. (C) 2001 Americ an Institute of Physics.