title: Influence of static atomic displacements on composition quantification of AlGaN/GaN heterostructures from HAADF-STEM images.
abstract: In an earlier publication Rosenauer et al. introduced a method for determination of composition in AlGaN/GaN heterostructures from high-angle annular dark field (HAADF) images. Static atomic displacements (SADs) were neglected during simulation of reference data because of the similar covalent radii of Al and Ga. However, SADs have been shown (Grillo et al.) to influence the intensity in HAADF images and therefore could be the reason for an observed slight discrepancy between measured and nominal concentrations. In the present study parameters of the Stillinger-Weber potential were varied in order to fit computed elastic constants, lattice parameters and bonding energies to experimental ones. A reference data set of HAADF images was simulated, in which the new parameterization was used to account for SADs. Two reference samples containing AlGaN layers with different Al concentrations were investigated and Al concentrations in the layers determined based on the new data set. We found that these concentrations were in good agreement with nominal concentrations as well as concentrations determined using alternative techniques such as strain state analysis and energy dispersive X-ray spectroscopy.
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Schowalter
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Stoffers
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Florian F
authors.initials: FF
authors.lastname: Krause
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Mehrtens
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Knut
authors.initials: K
authors.lastname: Müller
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Fandrich
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Aschenbrenner
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Hommel
authors.affiliation: Institut für Festkörperphysik,Universität Bremen,Otto-Hahn-Allee 1,28359 Bremen,Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rosenauer