Adsorption of Sn onSi(111)7 × 7: reconstructions in the monolayer regime

Törnevik, C.; Göthelid, Mats; Hammar, Mattias; Karlsson, Ulf O.; Nilsson, N.G.; Flodström, S. A.; Wigren, C.; Östling, Mikael

doi:10.1016/0039-6028(94)90005-1

Cited by 69 publications

(31 citation statements)

References 14 publications

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“…The brightness of the substituting Sn atoms is enhanced in the filled state image of Fig. 5b, indicated a charge transfer from the surrounding Si atoms, as was reported for Sn atoms in the mosaic √ 3 × √ 3 [11]. In addition to the 7 × 7 and mosaic domains, dark regions and trenches between the mosaic domains are observed.…”

Section: Resultssupporting

confidence: 55%

“…Figure 5a shows an empty state image and Fig. 5b a filled state image obtained at the same area after annealing at 880 • C. Most of the deposited Sn has been desorbed from the surface, and the 7 × 7 reconstruction reappears in the upper-right side of the figure, together with mosaic √ 3 × √ 3 domains [11,12]. However, the 7 × 7 structure is slightly different from the clean 7 × 7 structure, and the substitutional Sn atoms for adatom sites is partly observed as bright protrusions because of the larger covalent radius than Fig.…”

Section: Resultsmentioning

confidence: 94%

“…It is well known that Sn deposition in the coverage range from one-third up to one monolayer (ML) yields two coexisting surface superstructures, √ 3 × √ 3 and 2 √ 3 × 2 √ 3 [5,6]. Their atomic and electronic structures have been extensively investigated using scanning tunneling microscopy (STM) [7][8][9][10][11][12][13], surface X-ray diffraction [14] angle-resolved ultraviolet photoelectron spectroscopy (ARUPS), and k-resolved inverse photoelectron spectroscopy (KRIPES) [15,16]. In addition, because of its zero band gap [17], the formation of substratestabilized films of α-Sn, which is stable above the normal α-Sn to β-Sn transition temperature (13.2 • C), is desired for fabricating quantum well structures with unique electronic features [18].…”

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confidence: 99%

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STM observation of Sn overlayers on Si(111)

Yoshimura¹,

An²,

Yokogawa³

et al. 1998

Applied Physics A: Materials Science & Processing

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Atomic structures of tin overlayers on the surface of Si(111) have been investigated using scanning tunneling microscopy (STM). The surface reconstructions of √ 133 × 4 √ 3 and 3 √ 7 × 3 √ 7, that appear at the coverages above 1 monolayer, have been observed in real space for the first time. It is found that the former consists of three or four one-dimensional columns of zigzag chains, while the latter consists of two-dimensional honeycomb structures. The two phases coexist as small domains on the terrace with three different orientations reflecting the substrate symmetry. After desorption of the Sn, Sn atoms are observed partly replacing the Si adatom sites of 7 × 7 reconstruction. A charge transfer from the surrounding Si adatoms of 7 × 7 is suggested by the voltage dependence of the STM images.Tin belongs to the same column of the periodic table as the elemental semiconductors silicon and germanium, and it is an essential material in silicon device technology as a surfactant for the epitaxial growth of Si/Si [1, 2] and Ge/Si [3,4]. It is well known that Sn deposition in the coverage range from one-third up to one monolayer (ML) yields two coexisting surface superstructures, √ 3 × √ 3 and 2 √ 3 × 2 √ 3 [5, 6]. Their atomic and electronic structures have been extensively investigated using scanning tunneling microscopy (STM) [7][8][9][10][11][12][13], surface X-ray diffraction [14] angle-resolved ultraviolet photoelectron spectroscopy (ARUPS), and k-resolved inverse photoelectron spectroscopy (KRIPES) [15,16]. In addition, because of its zero band gap [17], the formation of substratestabilized films of α-Sn, which is stable above the normal α-Sn to β-Sn transition temperature (13.2 • C), is desired for fabricating quantum well structures with unique electronic features [18]. However, little work has been reported on surface structures above 1 ML. Ichikawa, using reflection highenergy electron diffraction (RHEED), found three different phases,, although the real-space atomic structure of these surfaces is not clear.In this paper, we present scanning tunneling microscopy (STM) observations of Sn overlayers on Si(111), paying special attention to the superstructures that appear at above 1 ML of Sn. The atomic structures of the two phases, √ 133 × 4 √ 3 and 3 √ 7 × 3 √ 7, have been revealed in real space by STM for the first time. It is found that the first structure is onedimensional, and the second is two-dimensional. In addition, we investigate the evolution of surface structures during the desorption of Sn by annealing at elevated temperatures. ExperimentalThe samples were cut from wafers of Si(111). The surfaces were cleaned by degassing at 600 • C overnight, followed by a repeated flashing at 1150 • C and a slow cool to room temperature. The surface prepared by this procedure showed large, and flat area of 7 × 7 reconstruction. A few monolayers of Sn were evaporated from a tungsten filament onto the substrates at room temperature. Then the substrates were annealed stepwise at elevated temperatures. The STM obs...

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Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 94%

mentioning

confidence: 99%

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STM observation of Sn overlayers on Si(111)

Yoshimura¹,

An²,

Yokogawa³

et al. 1998

Applied Physics A: Materials Science & Processing

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“…Special attention has been paid to mosaic phases of two-dimensional (2D) alloys with ( √ 3× √ 3)R30 • symmetry (hereafter denoted as √ 3× √ 3 for simplicity). These structures are usually induced by desorption of metal atoms (Pb [1][2][3], Sn [4,5], Tl [6,7]) together with their substitution by Si atoms.…”

Section: Introductionmentioning

confidence: 99%

Desorption-induced structural changes of metal/Si(111) surfaces: Kinetic Monte Carlo simulations

2013

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We used a configuration-based kinetic Monte Carlo model to explain important features related to formation of the (√3×√3)R30° mosaic of metal and semiconductor atoms on the Si(111) surface. Using first-order desorption processes, we simulate the surprising zero-order desorption spectra, reported in some cases of metal desorption from the Si(111) surface. We show that the mechanism responsible for the zerolike order of desorption is the enhanced desorption from disordered areas. Formation of the √3×√3 mosaic with properties of a strongly frustrated antiferromagnetic Ising model is simulated by a configuration-sensitive desorption. For substitution of desorbed metal atoms by Si adatoms, fast diffusion of the adatoms on top of a 1×1 layer is proposed as the most probable. Simulations of desorption-induced structural transitions provide us a link between underlying atomistic processes and the observed evolving morphologies with resultant macroscopic desorption fluxes. An effect of the desorption sensitivity on a configuration of neighboring atoms is emphasized.

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“…This annealing temperature has earlier been reported to give )ϫ) surfaces with the lowest defect density ͑substitutional Si atoms͒. 12 The amount of Sn deposited onto the surfaces, Sn , in monolayers ͑ML͒ has been used to label the different sample preparations. We do not claim that these numbers correspond exactly to the absolute coverage.…”

mentioning

confidence: 99%

Electronic structure ofSn/Si(111)3
Uhrberg
¹
,
Zhang
²
,
Balasubramanian
³

et al. 2000
Phys. Rev. B
56
12
43
0
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The Sn/Si͑111͒ )ϫ) surface has been studied by photoelectron spectroscopy, low-energy electron diffraction ͑LEED͒, and scanning tunneling microscopy. Unlike Sn/Ge͑111͒, the Sn/Si͑111͒ surface shows a )ϫ) LEED pattern at low temperature also ͑70 K͒. The electronic structure, however, is inconsistent with a pure )ϫ) phase. Sn 4d spectra exhibit two major components and the valence band shows two surface bands. These features have been associated with the low-temperature 3ϫ3 phase in the case of Sn/Ge͑111͒. The similarity in the electronic structure points to stabilization of a low-temperature phase for Sn/Si͑111͒ also, but at a significantly lower temperature ͑Ͻ70 K͒.Phase transitions in low-dimensional systems have recently attracted a lot of experimental and theoretical interest. A striking example is the transition that occurs on the 1 Pb/ Ge͑111͒ and 2 Sn/Ge͑111͒ surfaces. The room-temperature )ϫ) reconstruction, with 1 3 monolayer of Pb or Sn adatoms, changes gradually to a 3ϫ3 phase when the temperature is lowered. As determined by surface x-ray diffraction, 3,4 the transition to the 3ϫ3 phase involves vertical atomic displacements in the adatom layer which give rise to sharp 3ϫ3 low-energy electron diffraction ͑LEED͒ spots. Scanning tunneling microscopy ͑STM͒ images of these surfaces show a transition from a )ϫ) to a 3ϫ3 unit cell, which has been attributed to the formation of a commensurate charge-density wave.1,2 Other electronic structure studies, concentrated on the Sn/Ge͑111͒ system, have been done by photoelectron spectroscopy.5-7 An interesting and rather puzzling result is that the electronic structures of the )ϫ) and 3ϫ3 surfaces are qualitatively quite similar. The two major Sn 4d components and the two surface-state bands that are observed find a natural explanation in a 3ϫ3 surface phase but are not directly accounted for in a )ϫ) periodicity.Although the Pb/Si͑111͒ and Sn/Si͑111͒ systems can be expected to behave in a similar way to their Ge͑111͒ counterparts, they have been much less studied. The fact that there is no report of a )ϫ) to 3ϫ3 transition on the Sn/Si͑111͒ surface seems to be reflected in the lower number of publications for this system. It is known, however, that the Sn 4d core level of the Sn/Si͑111͒ )ϫ) surface shows an unexpected second component.8 Inspired by this situation, we have used several techniques to address the interesting atomic and electronic structure of Sn/Si͑111͒.The Sn/Si͑111͒ )ϫ) surface has been studied using photoelectron spectroscopy, LEED, and STM. Various Sn coverages were investigated in order to find the optimum preparation of the )ϫ) surface. The use of roomtemperature STM allowed us to check the quality of the surfaces and to characterize the different types of defects that are present. In contrast to the Sn/Ge͑111͒ system, we do not observe any transition to a 3ϫ3 phase in LEED at temperatures down to 70 K, which was the lowest temperature in this study. Despite this difference we find that both the Sn 4d core-level and valence-band spectra show the...

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Adsorption of Sn onSi(111)7 × 7: reconstructions in the monolayer regime

Cited by 69 publications

References 14 publications

STM observation of Sn overlayers on Si(111)

STM observation of Sn overlayers on Si(111)

Desorption-induced structural changes of metal/Si(111) surfaces: Kinetic Monte Carlo simulations

Electronic structure ofSn/Si(111)3
Uhrberg
¹
,
Zhang
²
,
Balasubramanian
³

et al. 2000
Phys. Rev. B
56
12
43
0
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Adsorption of Sn onSi(111)7 × 7: reconstructions in the monolayer regime

Cited by 69 publications

References 14 publications

STM observation of Sn overlayers on Si(111)

STM observation of Sn overlayers on Si(111)

Desorption-induced structural changes of metal/Si(111) surfaces: Kinetic Monte Carlo simulations

Electronic structure ofSn/Si(111)3Uhrberg1, Zhang2, Balasubramanian3 et al. 2000Phys. Rev. B5612430View full textAdd to dashboardCite

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Electronic structure ofSn/Si(111)3
Uhrberg
¹
,
Zhang
²
,
Balasubramanian
³

et al. 2000
Phys. Rev. B
56
12
43
0
View full text Add to dashboard Cite