Stoichiometry determination of chalcogenide superlattices by means of X-ray diffraction and its limits

TL;DR

This paper investigates the use of X-ray diffraction to determine the stoichiometry of chalcogenide superlattices, demonstrating a non-destructive method that follows Vegard's law for accurate composition analysis.

Contribution

It introduces a method combining X-ray diffraction and kinematical scattering theory to accurately determine superlattice stoichiometry non-destructively.

Findings

Lattice constants follow Vegard's law in the studied superlattices.

X-ray diffraction can reliably determine composition.

The method is applicable to phase-change memory materials.

Abstract

In this paper we explore the potential of stoichiometry determination for chalcogenide superlattices, promising candidates for next-generation phase-change memory, via X-ray diffraction. To this end, a set of epitaxial GeTe/Sb2Te3 superlattice samples with varying layer thicknesses is sputter-deposited. Kinematical scattering theory is employed to link the average composition with the diffraction features. The observed lattice constants of the superlattice reference unit cell follow Vegard's law, enabling a straight-forward and non-destructive stoichiometry determination.