Determination of in-depth thermal strain distribution in Molecular Beam Epitaxy GaAs on Si

Abstract

In-depth stress distribution GaAs layers grown by Molecular Beam Epitaxy (MBE) on Si (001) has been studied by X-ray diffraction, photoluminescence and Raman spectroscopy. In order to determine the stress state at different distances to the interface GaAs/Si, layers of different thickness were prepared by chemical etching of the grown samples. We observe a non-uniform residual strain distribution through the GaAs on Si epilayer. Residual strain of thermal origin is larger in the highly defective region (∼ 0.4 μm) near the GaAs/Si interface where we have found a non-elastic relation between measured in-plane (a _‖) and in growth direction (a _⊥) lattice parameters. However, thermal strain is partially relaxed by formation of 10⁷ cm⁻² dislocations in the region of better crystalline quality near the external surface.