Simulation Studies of a Composition Analysis by Thickness-Fringe (CAT) in an Electron Microscope Image of GaAs/Al_xGa_1-xAs Superstructure

Abstract

The intensity distribution of thickness fringes, observed at the edge of a cleaved chip of GaAs/Al x Ga 1- x As superstructure using a transmission electron microscope, was computer-simulated by means of the dynamical theory of electron diffraction. It was theoretically verified that the distance of a thickness fringe from the edge of a chip systematically changes, depending on the Al composition (experimentally found by the present authors (H. Kakibayashi and F. Nagata: Jpn. J. Appl. Phys. 24 (1985) L905)). The precise composition profile in the heterointerface and the most suitable observation condition for a composition analysis were studied using the simulation technique.