Indium<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mn>7</mml:mn></mml:msqrt><mml:mo>×</mml:mo><mml:msqrt><mml:mn>3</mml:mn></mml:msqrt></mml:math>on Si(111): A Nearly Free Electron Metal in Two Dimensions

Rotenberg, Eli; Koh, HyeJung; Roßnagel, Kai; Yeom, Han Woong; Schäfer, J.; Krenzer, B.; Rocha, Matthew P.; Kevan, S. D.

doi:10.1103/physrevlett.91.246404

Cited by 115 publications

(77 citation statements)

References 17 publications

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“…2(c) in Ref. [7]). This clearly indicates that the rect structure which has been investigated by the ARPES and is also assumed to be responsible for the electron transport at low temperature [2,5] is not the 1.…”

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confidence: 90%

“…The excess In atoms are desorbed from the surface in the annealing. The metallic behavior [2,7] and the superconducting gap [5] have been observed on the rect structure, whereas the metallic behavior and the superconducting current has been measured on the hex structure [6]. Identification of the hex and the rect structures based on the firstprinciples calculations is highly demanded.…”

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confidence: 99%

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Identification of metallic phases of In atomic layers on Si(111) surfaces

Uchida

Oshiyama

2013

Phys. Rev. B

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We report first-principles calculations that clarify atomic structures and coverage of the metallic phases of In overlayers on Si (111) surfaces. Calculated energy bands and scanning tunneling microscopy images along with the obtained energetics of various phases reveal that the two metallic phases with the √ 7 × √ 3 periodicity observed experimentally are single and double In overlayers, as opposed to prevailing assignments. PACS numbers: 68.43.Bc, 73.20.At, Surfaces ubiquitous in nature provide new phases of materials due to symmetry breaking and modification of interactions among constituting elements. A thin layer of metallic elements on a semiconductor surface is an example. It offers a good stage to study two-dimensional electron systems (2DESs), and also a key structure in device fabrication in current technology encountered with the cutting-edge miniaturization [1].Indium adatom layers on Si(111) surfaces are typical and important examples. A particular phase with the lateral periodicity of √ 7 × √ 3 exhibits metallic behavior down to several K [2], as opposed to the metalinsulator transition predicted for the 2DESs [3,4], and eventually becomes superconducting at 3 K [5,6]. This is the first case where superconductivity is found in a deposited layer. Angle-resolved photoemission spectroscopy (ARPES) clarifies the band structure of the metallic phase of the √ 7 × √ 3 surface [7]. However, atom-scale identification, i.e., the In coverage, the stable atomic structure and the resultant electron states, of the metallic phase is still lacking.Various surface reconstructions emerge by depositing In atoms on the Si(111) 7 × 7 surface [8], followed by annealing at ∼ 500• C in ultra-high vacuum: The √ 3 × √ 3, the √ 31 × √ 31, and the 4 × 1 phases appear consecutively with increasing the In dose, all showing insulating behavior at low temperature [9,10]. Then the √ 7 × √ 3 phase [11] appears with the In deposition of 1.5 -1.8 ML. The STM topographs [9,11] show that the two distinctive structures coexist on the √ 7 × √ 3 phase: Bright spots appear in a quasi-hexagonal pattern with protruding trimers in one structure (hex structure hereafter), and they appear in a quasi-rectangular pattern in the other structure (rect structure). The former and the latter have been speculated to be 1.0 ML and 1.2 ML, respectively, In adatoms on the Si(111) surface [9,11]. The excess In atoms are desorbed from the surface in the annealing. The metallic behavior [2,7] and the superconducting gap [5] have been observed on the rect structure, whereas the metallic behavior and the superconducting current has been measured on the hex structure [6]. Identification of the hex and the rect structures based on the firstprinciples calculations is highly demanded.In this Letter, we unequivocally identify the two metallic phases of √ 7 × √ 3 -In/Si(111) by performing totalenergy electronic-structure calculations in the densityfunctional theory. The obtained energetics, energy bands and scanning tunneling microscopy (STM) images are indicative t...

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confidence: 99%

Identification of metallic phases of In atomic layers on Si(111) surfaces

Uchida

Oshiyama

2013

Phys. Rev. B

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“…One representative system of recent interest is the In/Si(111)-( √ 7× √ 3) surface, where the In overlayer was generally assumed to be one atom thick [6][7][8] and so represent an ideal two-dimensional (2D) limit of metallic In properties. Fascinating electronic features of the In overlayer, including a nearlyfree-electron Fermi surface, [9], superconducting transitions [10,11], and an intriguing metallic transport behavior [12], have been explored and referred to as revealing the ultimate 2D limit. With little structural information about the In overlayer, however, its actual layer thickness has long been an open question.…”

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Hexagonal indium double layer onSi(111)−7×3

Park

Kang

2015

Phys. Rev. B

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“…In this sense, we call this a final-state effect. Whether the observed photoemission spectra is due to the initial-or final-state effect has been debated for several systems such as the Si͑111͒ ͱ 21ϫ ͱ 21-Ag, -͑Ag,Au͒ surfaces 37,38 or Si͑111͒ ͱ 7 ϫ ͱ 3-In, 39 but it has been difficult to determine which is correct. Similarly, it is also difficult to conclude which of the effects is the reason for the presently observed ͱ 3 ϫ ͱ 3 periodicity of the QWSs.…”

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confidence: 99%

Manipulating quantum-well states by surface alloying: Pb on ultrathin Ag films

et al. 2008

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The electronic structure of ultrathin Ag films with 1/3 monolayer ͑ML͒ of Pb alloyed at the surface was investigated by angle-resolved photoemission spectroscopy. Compared to clean ultrathin Ag films, the energy positions of the quantum-well states ͑QWSs͒ moved closer to the Fermi level due to the change of the potential barrier at the film/vacuum interface. We found that the parabolic band dispersion of the QWSs become disturbed where they cross the surface-state bands, and furthermore, they were shown to follow the periodicity that is only present at the surface. Our results suggest that it is possible to tune the properties of the QWSs whose thickness is more than 10 ML just by submonolayer deposition of heteroelements at the surface.

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Indium7×3on Si(111): A Nearly Free Electron Metal in Two Dimensions

Cited by 115 publications

References 17 publications

Identification of metallic phases of In atomic layers on Si(111) surfaces

Identification of metallic phases of In atomic layers on Si(111) surfaces

Hexagonal indium double layer onSi(111)−7×3

Manipulating quantum-well states by surface alloying: Pb on ultrathin Ag films

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