Details
| Original language | English |
|---|---|
| Article number | 013401 |
| Journal | Physical Review Materials |
| Volume | 4 |
| Issue number | 1 |
| Publication status | Published - 9 Jan 2020 |
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.
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Physics and Astronomy (miscellaneous)
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In: Physical Review Materials, Vol. 4, No. 1, 013401, 09.01.2020.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Matching different symmetries with an atomically sharp interface
T2 - Epitaxial Ba2SiO4 on Si(001)
AU - Koch, Julian
AU - Müller-Caspary, Knut
AU - Pfnür, Herbert
N1 - Funding information: K.M.-C. acknowledges funding from the Initiative and Network Fund of the Helmholtz Association under Contract No. NG-1317.
PY - 2020/1/9
Y1 - 2020/1/9
N2 - 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.
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.
UR - http://www.scopus.com/inward/record.url?scp=85078323981&partnerID=8YFLogxK
U2 - 10.1103/PhysRevMaterials.4.013401
DO - 10.1103/PhysRevMaterials.4.013401
M3 - Article
AN - SCOPUS:85078323981
VL - 4
JO - Physical Review Materials
JF - Physical Review Materials
IS - 1
M1 - 013401
ER -