<title>Reciprocal lattice mapping of InGaAs layers grown on InP(001) and GaAs(001) substrates</title>

Abstract

The structure of InGaAs (InAs) layers grown on InP (001) and GaAs (001) surfaces by Molecular Beam Epitaxy was studied by high-resolution x-ray diffractometry. The reciprocal lattice mapping and the rocking curve technique were used to determine distribution of misfit dislocations in the layers. Directional dependence of dislocation density in InGaAs strained layers grown at 2D growth mode was observed. It was found that anisotropic distribution of dislocations in the InGaAs layers resulted from development via bending in the interface plane of dislocations present in the InP substrate. Simultaneously, homogeneous distribution of dislocations in relaxed InAs layers grown on InP as well as GaAs substrates has been detected. At the initial stage these epitaxial layers were grown to 3D island mode. The reciprocal lattice maps confirm that coalescence of islands during the epitaxy generates dislocations, which in turn homogeneously distribute in the layer. It seems that the growth mode rather than lattice mismatch determines density of dislocations in InAs epitaxial layers grown on InP and GaAs substrates. However, lattice mismatch influences relaxation process in lattice-mismatched layers. Transport properties of relaxed InAs layers strongly depend on growth temperature.