Journal Article

FZJ-2021-02906

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Matching different symmetries with an atomically sharp interface: Epitaxial Ba 2 SiO 4 on Si(001)

Koch, J. (Corresponding author) ; Müller-Caspary, K.FZJ* ; Pfnür, H.

2020
APS College Park, MD

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Please use a persistent id in citations: http://hdl.handle.net/2128/28092  doi:10.1103/PhysRevMaterials.4.013401

Abstract: In this paper, we present a comprehensive investigation of the epitaxial growth of Ba2SiO4 on Si(001), a system in which neither crystal symmetry nor lattice constants match in a simple manner. In addition, it has the potential to become the first crystalline high-k gate dielectric. We combined x-ray photoelectron spectroscopy, low-energy electron diffraction, and aberration-corrected scanning transmission electron microscopy (STEM) in order to optimize the epitaxial growth by molecular beam epitaxy. Our focus was on the formation of a high quality crystalline interface. The films were grown by a co-deposition method that requires no diffusion of Si from the substrate. An annealing temperature of 400∘C turned out to be sufficient to form chemically homogeneous films. However, crystalline films require an annealing step to 670–690∘C for the formation of the epitaxial interface necessary for breaking Si-O bonds. STEM confirms that the interface is atomically sharp and that a single layer of the silicate is changed to a (2×3) structure at the interface from the (2×1.5) bulk structure. Based on our experimental results, we propose a geometrical model for the epitaxial interface. The growth of films with an understoichiometric Si flux leads to the formation of a near-surface Ba silicide that does not restrict the epitaxial silicate growth.

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Contributing Institute(s):

1. Physik Nanoskaliger Systeme (ER-C-1)

Research Program(s):

1. 5351 - Platform for Correlative, In Situ and Operando Characterization (POF4-535) (POF4-535)
2. moreSTEM - Momentum-resolved Scanning Transmission Electron Microscopy (VH-NG-1317) (VH-NG-1317)

Appears in the scientific report 2021

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Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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