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Title: One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111)

Abstract

Ge nanostructures grown by molecular beam epitaxy on a vicinal Si(111) surface with atomically well-defined steps are studied by means of scanning tunneling microscopy and spectroscopy. When the substrate temperature during deposition is around 250 degree sign C, Ge nanoclusters of diameters less than 2.0 nm form a one-dimensional array of the periodicity 2.7 nm along each step. This self-organization is due to preferential nucleation of Ge on the unfaulted 7x7 half-unit cells at the upper step edges. Scanning tunneling spectroscopy reveals localized electronic states of the nanoclusters.

Authors:
; ; ; ;  [1];  [2]
  1. Department of Applied Physics and Physico-Informatics, Keio University, 3-14-1, Hiyoshi, Kokohu-ku, Yokohama 223-8522 (Japan) and Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi Center Building, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
  2. (Germany)
Publication Date:
OSTI Identifier:
20883256
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 1; Other Information: DOI: 10.1063/1.2426890; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMIC CLUSTERS; CRYSTAL GROWTH; DEPOSITION; GERMANIUM; LAYERS; MOLECULAR BEAM EPITAXY; NANOSTRUCTURES; NUCLEATION; SCANNING TUNNELING MICROSCOPY; SEMICONDUCTOR MATERIALS; SILICON; SPECTROSCOPY; SUBSTRATES

Citation Formats

Sekiguchi, Takeharu, Yoshida, Shunji, Itoh, Kohei M., Myslivecek, Josef, Voigtlaender, Bert, and Institute of Bio and Nanosystems IBN3, Research Center Juelich and Center of Nanoelectric Systems for Information Technology, 52425 Juelich. One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111). United States: N. p., 2007. Web. doi:10.1063/1.2426890.
Sekiguchi, Takeharu, Yoshida, Shunji, Itoh, Kohei M., Myslivecek, Josef, Voigtlaender, Bert, & Institute of Bio and Nanosystems IBN3, Research Center Juelich and Center of Nanoelectric Systems for Information Technology, 52425 Juelich. One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111). United States. doi:10.1063/1.2426890.
Sekiguchi, Takeharu, Yoshida, Shunji, Itoh, Kohei M., Myslivecek, Josef, Voigtlaender, Bert, and Institute of Bio and Nanosystems IBN3, Research Center Juelich and Center of Nanoelectric Systems for Information Technology, 52425 Juelich. Mon . "One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111)". United States. doi:10.1063/1.2426890.
@article{osti_20883256,
title = {One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111)},
author = {Sekiguchi, Takeharu and Yoshida, Shunji and Itoh, Kohei M. and Myslivecek, Josef and Voigtlaender, Bert and Institute of Bio and Nanosystems IBN3, Research Center Juelich and Center of Nanoelectric Systems for Information Technology, 52425 Juelich},
abstractNote = {Ge nanostructures grown by molecular beam epitaxy on a vicinal Si(111) surface with atomically well-defined steps are studied by means of scanning tunneling microscopy and spectroscopy. When the substrate temperature during deposition is around 250 degree sign C, Ge nanoclusters of diameters less than 2.0 nm form a one-dimensional array of the periodicity 2.7 nm along each step. This self-organization is due to preferential nucleation of Ge on the unfaulted 7x7 half-unit cells at the upper step edges. Scanning tunneling spectroscopy reveals localized electronic states of the nanoclusters.},
doi = {10.1063/1.2426890},
journal = {Applied Physics Letters},
number = 1,
volume = 90,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Engineered wafer systems are an important materials science approach to achieve the global integration of single crystalline Ge layers on the Si platform. Here, we report the formation of single crystalline, fully relaxed Ge(111) films by molecular beam epitaxial overgrowth of cubic Pr oxide buffers on Si(111) substrates. Reflection high-energy electron diffraction, scanning electron microscopy, and x-ray reflectivity show that the Ge epilayer is closed, flat, and has a sharp interface with the underlying oxide template. Synchrotron radiation grazing incidence x-ray diffraction and transmission electron microscopy reveal the type-A/B/A epitaxial relationship of the Ge(111)/cubic Pr{sub 2}O{sub 3}(111)/Si(111) heterostructure, a resultmore » also corroborated by theoretical ab initio structure calculations. Secondary ion mass spectroscopy confirms the absence of Pr and Si impurities in the Ge(111) epilayer, even after an annealing at 825 deg. C.« less
  • Abstract not provided.
  • Angle resolved photoemission measurements have been carried out for Ge(111)-c(2 x 8), Ge(111)-(1 x 1)H, Si(111)-(7 x 7), and Si(100)-(2 x 1) in a normal emission geometry over a wide photon energy range. For Ge(111) and Si(100), dispersive bulk-derived transitions were observed, from which the authors have determined the bulk valence-band dispersion relations for Ge along the (111) direction and for Si along the (100) direction in the Brillouin zone. The results are compared with the theoretical band dispersions of Chelikowsky and Cohen. For Si(111)-(7 x 7), the spectra are dominated by nondispersive features which cannot be used for bandmore » mapping. The lack of dispersive bulk-transition features for Si(111)-(7 x 7) is explained in terms of a relatively extended near-surface strain field which renders the electron crystal momentum highly mixed. Several surface-state features on these surfaces were also observed; most of them are visible over a very wide photon energy range and are indeed dispersionless, confirming the previous surface-state assignments. 31 references, 6 figures.« less
  • The formation of three-dimensional (3D) structures during Ge deposition on Si(111) at about 800 °C is studied with scanning tunneling, Kelvin probe and electron microscopies, and scanning tunneling and Raman spectroscopies. The observed surface morphology is formed by dewetting of Ge from Si(111), since it occurs mainly by means of minimization of surface and interfacial energies. The dewetting proceeds through massive Si eroding around growing 3D structures, providing them to be composed of SiGe with about a 30% Ge content, and leads to the significant reduction of the SiGe/Si interface area. It is found that the SiGe top component of 3Dmore » structures forms sharp interfaces with the underlying Si. The minimization of interfacial and strain energies occurs on the way that the 3D structures appear to get the dendrite-like shape. The Ge distribution in the 3D SiGe structures is inhomogeneous in the lateral dimension with a higher Ge concentration in their central areas and Ge segregation on their surface.« less