title: Combining moiré patterns and high resolution transmission electron microscopy for in-plane thin films thickness determination.
abstract: This paper reports the coupling of HRTEM and moiré pattern observations, allowing the determination of the thickness ratio of two superimposed crystals. Pseudo-lattice fringes are observed using identical TEM experimental conditions as for observing moiré patterns. The pseudo-lattice spacing is first calculated in the dynamical theory framework in two beam conditions. This approach shows a linear behavior of the spacing as a function of the thickness ratio of the two crystals. The roles of sample crystallographic orientation and sample thickness on the thickness ratio determination are discussed from multi-beam simulations. Finally, the method is applied on a bimetallic CuAg core-shell nanoparticle of a known structure. It is demonstrated that for this particle, the thickness ratio of Cu and Ag can be determined with an error that results in a precision less than 0.75 nm on the Cu and Ag thicknesses. The advantages of the technique are the use of an in-plane sample configuration and a single HRTEM image.
authors.affiliation: Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR 7162, Université Paris Diderot--Paris 7, Case Courrier 7021, 75205 Paris Cedex 13, France.
authors.forename: M
authors.initials: M
authors.lastname: Valamanesh
authors.forename: C
authors.initials: C
authors.lastname: Langlois
authors.forename: D
authors.initials: D
authors.lastname: Alloyeau
authors.forename: E
authors.initials: E
authors.lastname: Lacaze
authors.forename: C
authors.initials: C
authors.lastname: Ricolleau
mesh_terms: D003461:Crystallography; D007091:Image Processing, Computer-Assisted; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D015903:Moire Topography / Q000379:methods*; D053758:Nanoparticles / Q000032:analysis*