X-ray interference in ultrathin epitaxial layers: A versatile method for the structural analysis of single quantum wells and heterointerfaces

Abstract

We report a versatile method to investigate the structural properties of ultrathin-epitaxial-layer structures by using the x-ray interference effect (Pendell\"osung). A detailed theoretical and experimental study on ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As/GaAs heterostructures shows that the intensity modulation of the interference fringes can be used to determine the thickness, the lattice strain, and the chemical composition of single-quantum-well structures as well as of laser and high-electron-mobility-transistor structures, and the strain at heterointerfaces. We show that epitaxial layers and transition regions at heterointerfaces having a thickness of one monolayer only can be detected experimentally and analyzed by using the dynamical x-ray diffraction theory.