Cobalt containing nano-islands on Ge(111)-c(2 x 8)

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Abstract

The structural and electronic properties of Co containing islands on Ge(111)-c(2 × 8) surfaces have been studied using scanning tunneling microscopy and spectroscopy. Room temperature deposition of a sub-monolayer amount of Co and subsequent annealing at 500 K lead to the formation of (√13 × √13)R13.9° reconstructed islands, whereas annealing at 750 K results in (2 × 2) reconstructed islands. The latter type of islands has heights up to several atomic layers. We find that, in analogy with Co on Si(111), the (2 × 2) islands consist of CoGe2, condensed in a fluorite structure. Each Co(111) layer is encapsulated between two close packed Ge layers, while the outermost trilayer is terminated by an additional layer of Ge adatoms in a (2 × 2) registry. The (√13 × √13)R13.9° structure can be considered as a precursor to the CoGe2 crystallites with triangular trilayer patches, composed of three embedded Co atoms terminated by six Ge adatoms. The remaining dangling bond transfers charge to surrounding Ge atoms in the bilayer. The different domains in the (2 × 2) islands are separated by three types of boundaries. Two types of domain boundaries are dynamic, whereas the third type of domain boundary is static. The (2 × 2) domains show a faint (6 × 2) superstructure, which is tentatively attributed to the aligned Co defects at the interface. Scanning tunneling spectroscopy measurements indicate the presence of Co atoms in the (2 × 2) and (√13 × √13)R13.9° reconstructed islands.
Original languageEnglish
Pages (from-to)59-64
JournalSurface science
Volume610
DOIs
Publication statusPublished - 2013

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cobalt
adatoms
atoms
annealing
fluorite
spectroscopy
crystallites
scanning tunneling microscopy
charge transfer
scanning
defects
room temperature
electronics

Keywords

  • METIS-295814
  • IR-89913

Cite this

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title = "Cobalt containing nano-islands on Ge(111)-c(2 x 8)",
abstract = "The structural and electronic properties of Co containing islands on Ge(111)-c(2 × 8) surfaces have been studied using scanning tunneling microscopy and spectroscopy. Room temperature deposition of a sub-monolayer amount of Co and subsequent annealing at 500 K lead to the formation of (√13 × √13)R13.9° reconstructed islands, whereas annealing at 750 K results in (2 × 2) reconstructed islands. The latter type of islands has heights up to several atomic layers. We find that, in analogy with Co on Si(111), the (2 × 2) islands consist of CoGe2, condensed in a fluorite structure. Each Co(111) layer is encapsulated between two close packed Ge layers, while the outermost trilayer is terminated by an additional layer of Ge adatoms in a (2 × 2) registry. The (√13 × √13)R13.9° structure can be considered as a precursor to the CoGe2 crystallites with triangular trilayer patches, composed of three embedded Co atoms terminated by six Ge adatoms. The remaining dangling bond transfers charge to surrounding Ge atoms in the bilayer. The different domains in the (2 × 2) islands are separated by three types of boundaries. Two types of domain boundaries are dynamic, whereas the third type of domain boundary is static. The (2 × 2) domains show a faint (6 × 2) superstructure, which is tentatively attributed to the aligned Co defects at the interface. Scanning tunneling spectroscopy measurements indicate the presence of Co atoms in the (2 × 2) and (√13 × √13)R13.9° reconstructed islands.",
keywords = "METIS-295814, IR-89913",
author = "T.F. Mocking and Bene Poelsema and Zandvliet, {Henricus J.W.}",
year = "2013",
doi = "10.1016/j.susc.2013.01.007",
language = "English",
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pages = "59--64",
journal = "Surface science",
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Cobalt containing nano-islands on Ge(111)-c(2 x 8). / Mocking, T.F.; Poelsema, Bene; Zandvliet, Henricus J.W.

In: Surface science, Vol. 610, 2013, p. 59-64.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Cobalt containing nano-islands on Ge(111)-c(2 x 8)

AU - Mocking, T.F.

AU - Poelsema, Bene

AU - Zandvliet, Henricus J.W.

PY - 2013

Y1 - 2013

N2 - The structural and electronic properties of Co containing islands on Ge(111)-c(2 × 8) surfaces have been studied using scanning tunneling microscopy and spectroscopy. Room temperature deposition of a sub-monolayer amount of Co and subsequent annealing at 500 K lead to the formation of (√13 × √13)R13.9° reconstructed islands, whereas annealing at 750 K results in (2 × 2) reconstructed islands. The latter type of islands has heights up to several atomic layers. We find that, in analogy with Co on Si(111), the (2 × 2) islands consist of CoGe2, condensed in a fluorite structure. Each Co(111) layer is encapsulated between two close packed Ge layers, while the outermost trilayer is terminated by an additional layer of Ge adatoms in a (2 × 2) registry. The (√13 × √13)R13.9° structure can be considered as a precursor to the CoGe2 crystallites with triangular trilayer patches, composed of three embedded Co atoms terminated by six Ge adatoms. The remaining dangling bond transfers charge to surrounding Ge atoms in the bilayer. The different domains in the (2 × 2) islands are separated by three types of boundaries. Two types of domain boundaries are dynamic, whereas the third type of domain boundary is static. The (2 × 2) domains show a faint (6 × 2) superstructure, which is tentatively attributed to the aligned Co defects at the interface. Scanning tunneling spectroscopy measurements indicate the presence of Co atoms in the (2 × 2) and (√13 × √13)R13.9° reconstructed islands.

AB - The structural and electronic properties of Co containing islands on Ge(111)-c(2 × 8) surfaces have been studied using scanning tunneling microscopy and spectroscopy. Room temperature deposition of a sub-monolayer amount of Co and subsequent annealing at 500 K lead to the formation of (√13 × √13)R13.9° reconstructed islands, whereas annealing at 750 K results in (2 × 2) reconstructed islands. The latter type of islands has heights up to several atomic layers. We find that, in analogy with Co on Si(111), the (2 × 2) islands consist of CoGe2, condensed in a fluorite structure. Each Co(111) layer is encapsulated between two close packed Ge layers, while the outermost trilayer is terminated by an additional layer of Ge adatoms in a (2 × 2) registry. The (√13 × √13)R13.9° structure can be considered as a precursor to the CoGe2 crystallites with triangular trilayer patches, composed of three embedded Co atoms terminated by six Ge adatoms. The remaining dangling bond transfers charge to surrounding Ge atoms in the bilayer. The different domains in the (2 × 2) islands are separated by three types of boundaries. Two types of domain boundaries are dynamic, whereas the third type of domain boundary is static. The (2 × 2) domains show a faint (6 × 2) superstructure, which is tentatively attributed to the aligned Co defects at the interface. Scanning tunneling spectroscopy measurements indicate the presence of Co atoms in the (2 × 2) and (√13 × √13)R13.9° reconstructed islands.

KW - METIS-295814

KW - IR-89913

U2 - 10.1016/j.susc.2013.01.007

DO - 10.1016/j.susc.2013.01.007

M3 - Article

VL - 610

SP - 59

EP - 64

JO - Surface science

JF - Surface science

SN - 0039-6028

ER -