Local estimation of lattice constants in HRTEM images

T Niermann; J B Park; M Lehmann

doi:10.1016/j.ultramic.2011.03.014

Local estimation of lattice constants in HRTEM images

Ultramicroscopy. 2011 Jul;111(8):1083-92. doi: 10.1016/j.ultramic.2011.03.014. Epub 2011 Mar 31.

Authors

T Niermann¹, J B Park, M Lehmann

Affiliation

¹ Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany. [email protected]

PMID: 21740872
DOI: 10.1016/j.ultramic.2011.03.014

Abstract

A model-based approach to estimate lattice constants from an atomically resolved HRTEM image is presented. The approach only utilizes the inherent periodicity of these images and does not require a centrosymmetric structure of the specimen. This allows the evaluation of, for instance, wurtzite-based materials like InGaN/GaN heterostructures. The lattice constants are determined within precisions below 3 pm from areas only a few unit cells large. This makes this method suitable for further strain/compositional analysis. Furthermore, the impact of the approximations of the true detector's covariance matrices on the assessment of the model-based approach is investigated, and insights into the quality of these noise models of the detector are gained.