Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 1: Nitrides: Preparation and characterization I
HL 1.8: Vortrag
Montag, 18. März 2024, 11:45–12:00, EW 015
HAXPES Study of Al1−xScxN-based Ferroelectric Capacitors — •Oliver Rehm1, Lutz Baumgarten2, Roberto Guido3, Pia Düring1, Andrei Gloskovskii4, Christoph Schlueter4, Thomas Mikolajick3,5, Uwe Schroeder3, and Martina Müller1 — 1Uni Konstanz, Konstanz, Germany — 2FZJ, Jülich, Germany — 3NaMLab, Dresden, Germany — 4DESY, Hamburg, Germany — 5TU Dresden, Dresden, Germany
The novel ferroelectric (FE) material Al1−xScxN exhibits a large remanent polarization and coercive field, with huge potential for the next generation of nonvolatile memory devices. However, the application of AlScN-based thin films as active FE is currently hampered by cycling endurance and leakage issues, which are worse than that of HfO2.
The present work focuses on exploring the chemical properties of Al0.83Sc0.17N thin films (60 nm) using hard x-ray photoelectron spectroscopy (HAXPES). Studying both W-capped and uncapped samples, we show that AlScN is not stable in air due to surface-enhanced oxidation over long periods (weeks to months). By comparing the contribution of Sc and Al relative to the overall oxidation of Al1−xScxN, we assume that oxygen tends to occupy a neighbour lattice site of Sc, resulting in an enhanced oxidation of Sc compared to Al. Moreover, the oxidation process causes N atoms to be removed from their lattice sites, likely leading to an incorporation of interstitial N, which is deduced from the observation of a surface-enhanced spectral feature of the N 1s core-level.
O. Rehm, L. Baumgarten, M. Müller et al., in preparation
Keywords: HAXPES; Photoelectron spectroscopy; AlScN; ferroelectric