A method for thin foil thickness determination by transmission electron microscopy

It is often desirable in transmission electron microscopy to know the vertical spacing of points of interest within a specimen. However, in order to measure a stereo effect, one must have two pictures of the same area taken from different angles, and one must have also a formula for converting measured differences between corresponding points (parallax) into a height differential.Assume (a) that the impinging beam of electrons can be considered as a plane wave and (b) that the magnification is the same at the top and bottom of the specimen. The first assumption is good when the illuminating system is overfocused. The second assumption (the so-called “perspective error”) is good when the focal length is large (3 x 107Å) in relation to foil thickness (∼103 Å).

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Determination of segregation, elastic strain and thin-foil relaxation in InxGa-1-x As islands on GaAs(001) by high resolution transmission electron microscopy

Philosophical Magazine Letters ◽

10.1080/095008396180029 ◽

1996 ◽

Vol 74 (5) ◽

pp. 309-315 ◽

Cited By ~ 33

Author(s):

K. Tillmann ◽

A. Thust ◽

M. Lentzen ◽

P. Swiatek ◽

A. FÖRSTER ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Elastic Strain ◽

Thin Foil ◽

Transmission Electron

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Transmission Electron Microscopy of Strained-Layer Superlattices

MRS Proceedings ◽

10.1557/proc-37-267 ◽

1984 ◽

Vol 37 ◽

Author(s):

J. M. Gibson ◽

M. M. J. Treacy ◽

R. Hull ◽

J. C. Bean

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Thin Foil ◽

Local Variation ◽

Atomic Displacement ◽

Shear Stresses ◽

Local Composition ◽

Strained Layer ◽

Transmission Electron ◽

Strained Layer Superlattice

Transmission electron microscopy provides a powerful means of studying compositionally modulated materials. In such materials there is usually a local variation in electron scattering power along with a lattice dilatation wave which both accompany the local composition. The most revealing geometry for studying such materials has the lattice modulation direction lying within the plane of the thin foil. However, shear stresses accompanying the dilatation wave can be significantly relaxed by the presence of the thin foil surfaces, modifying the local atomic displacement field such that it is representative of neither the bulk, nor the free unstressed material. Two pertinent semiconductor examples which we have studied are spinodally decomposed quaternary III–V layers and strainedlayer superlattices of Si/SixGe1−x. We provide experimental evidence demonstrating relaxation in these cases and a simple elasticity model to describe it. Our data and model show a thickness dependence to relaxation and can explain previously reported ‘anomalous’ lattice parameter measurements from a strained-layer superlattice [11]. In this paper we concentrate on the effects of dilatation and relaxation on imaging and diffraction from a strained-layer superlattice.

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