Concentration and relaxation depth profiles of InxGa1−xAs/GaAs and GaAs1−xPx/GaAs graded epitaxial films studied by x-ray diffraction

Abstract

A method is proposed to determine the concentration and relaxation depth profiles in graded epitaxial films from x-ray reciprocal space maps (RSMs). Various approximations in the kinematical x-ray diffraction from epitaxial films with the misfit dislocation density depth profile are developed. We show that a symmetric and an asymmetric RSM, or two asymmetric RSMs, contain enough information to obtain the concentration, relaxation, and lattice tilt depth profiles without any additional assumptions. The proposed approach is applied to In${}_{x}$Ga${}_{1\ensuremath{-}x}$As/GaAs and GaAs${}_{1\ensuremath{-}x}$P${}_{x}$/GaAs epitaxial graded films. The reconstructed concentration and dislocation density depth profiles are found to be in an agreement with the ones expected from the growth conditions.