The interpretation of the FOLZ reflection fine structure in CBED patterns of GaInAsP

Abstract

Abstract The fine structure of the first-order Laue zone (FOLZ) reflections in convergent-beam electron diffraction (CBED) patterns of Gaxln1–xAsyP1–y/InP heterostructures is investigated. The FOLZ reflection fine structure consists mainly of three bright lines; the position and intensity of these bright lines were used for a quantitative interpretation, using many-beam dynamical calculations. The main factor determining the position of the lines appears to be the composition. However, HOLZ-beam coupling, absorption and thermal vibrations of atoms have a considerable effect on the position and the intensity of the lines. Values of these parameters were estimated from the CBED patterns. A good agreement between calculation and experiment could only be obtained if small static displacements of the atoms from their ideal lattice sites were included. The calculations suggest that the static displacements in the quaternary compounds should be largest on the group-V sublattice. The quasi-periodic strain fields ...