TY  - JOUR
AU  - Koch, Julian
AU  - Müller-Caspary, Knut
AU  - Pfnür, Herbert
TI  - Matching different symmetries with an atomically sharp interface: Epitaxial Ba 2 SiO 4 on Si(001)
JO  - Physical review materials
VL  - 4
IS  - 1
SN  - 2475-9953
CY  - College Park, MD
PB  - APS
M1  - FZJ-2021-02906
SP  - 013401
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000506605500001
DO  - DOI:10.1103/PhysRevMaterials.4.013401
UR  - https://juser.fz-juelich.de/record/893894
ER  -