Chemical Tuning of Metal-Semiconductor Interfaces

Da, Ricci; Miller, T.; Chiang, TC

doi:10.1103/physrevlett.93.136801

Cited by 40 publications

(43 citation statements)

References 29 publications

(46 reference statements)

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“…158) By modifying the Si surface with different metals, the interface dependence of quantum wells was observed on Pb films. 159) Another work on the Ag films grown on 1D surface superstructure Si(111)-4 Â 1-In reported that the lateral energy dispersion of QWS showed clear 1D anisotropy instead of the isotropic 2D free-electronlike behavior as expected for an isolated metal film. 160) Modification of interface structure provides another way for modulating the QSE.…”

Section: Discussionmentioning

confidence: 99%

Quantum Size Effects Induced Novel Properties in Two-Dimensional Electronic Systems: Pb Thin Films on Si(111)

Jia

Zhang

et al. 2007

J. Phys. Soc. Jpn.

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Atomically flat metal ultrathin films grown on semiconductor substrates form a quasi-two-dimensional (2D) electronic system, which offers a great opportunity to explore novel properties induced by quantum size effects (QSE). In such a system, the motion of electrons in the film plane is essentially free, however, in the film normal direction it is confined, which leads to the quantized electronic states, i.e., quantum well states (QWS). The formation of QWS induces the redistribution of electrons and changes the electronic structure of the metal films and thus modifies their properties. By controlling the film thickness-the width of the confinement potential well, the QWS, together with the physical and chemical properties of the films can be engineered. In this article, we will summarize our recent studies on this problem in the Pb/Si(111) system, and discuss the perspectives in this area.

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Section: Discussionmentioning

confidence: 99%

Quantum Size Effects Induced Novel Properties in Two-Dimensional Electronic Systems: Pb Thin Films on Si(111)

Jia

Zhang

et al. 2007

J. Phys. Soc. Jpn.

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“…The growth conditions can depend significantly on the substrate crystal orientation 3 and on the interface reconstruction 4 . Furthermore the energies of the confined states can be altered via changing the atomic species at the interface 5 . In this work we will extend this research and show that also the band dispersion of quantum well states can be altered by interface engineering, exemplified by the system of ultra-thin Pb films on Si(111) .…”

Section: Introductionmentioning

confidence: 99%

Controlling the effective mass of quantum well states in Pb/Si(111) by interface engineering

et al. 2011

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The in-plane effective mass of quantum well states in thin Pb films on a Bi reconstructed Si (111) surface is studied by angle-resolved photoemission spectroscopy. It is found that this effective mass is a factor of 3 lower than the unusually high values reported for Pb films grown on a Pb reconstructed Si(111) surface. Through a quantitative low-energy electron diffraction analysis the change in effective mass as a function of coverage and for the different interfaces is linked to a change of about 2% in the in-plane lattice constant. To corroborate this correlation, density functional theory calculations are performed on freestanding Pb slabs with different in-plane lattice constants. These calculations show an anomalous dependence of the effective mass on the lattice constant including a change of sign for values close to the lattice constant of Si(111). This unexpected relation is due to a combination of reduced orbital overlap of the 6pz states and altered hybridization between the 6pz and the 6pxy derived quantum well states. Furthermore, it is shown by core-level spectroscopy that the Pb films are structurally and temporally stable at temperatures below 100 K. Controlling the effective mass of quantum well states in Pb/Si(111) by interface engineering The in-plane effective mass of quantum well states in thin Pb films on a Bi reconstructed Si(111) surface is studied by angle-resolved photoemission spectroscopy. It is found that this effective mass is a factor of three lower than the unusually high values reported for Pb films grown on a Pb reconstructed Si(111) surface. Through a quantitative low-energy electron diffraction analysis the change in effective mass as a function of coverage and for the different interfaces is linked to a change of around 2 % in the in-plane lattice constant. To corroborate this correlation, density functional theory calculations were performed on freestanding Pb slabs with different in-plane lattice constants. These calculations show an anomalous dependence of the effective mass on the lattice constant including a change of sign for values close to the lattice constant of Si(111). This unexpected relation is due to a combination of reduced orbital overlap of the 6pz states and altered hybridization between the 6pz and 6pxy derived quantum well states. Furthermore it is shown by core level spectroscopy that the Pb films are structurally and temporally stable at temperatures below 100 K.

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“…The apparent quantum-versusclassical nature of the alloy films on the (7 × 7) and √ 3 interfaces could perhaps be attributed to differences in Schottky barrier height (or confinement barrier) at the substrate interface where the (7 × 7) interfaces usually exhibit higher Schottky barriers. 8,15,24 Alternatively, the Ga concentration gradient for the √ 3 interfaces might also weaken the vertical quantum interference that is necessary for establishing quantum growth. 25 The ramifications of the template choice on the superconductive properties will be discussed next.…”

Section: Resultsmentioning

confidence: 99%

“…Such template modification can facilitate smooth layer growth through surfactant 11,12 or interfactant action 13 or it can be used to control the band offset or Schottky barrier at the interface. 8,14,15 In this report, we show how the modification of a Si(111)-(7 × 7) template into a Si(111)-(…”

Section: Introductionmentioning

confidence: 99%

“…6,7 The substrate is essential in both cases because it determines the strain energy and quantum mechanical boundary conditions of the films. [6][7][8][9][10] Atomically-clean substrate surfaces are often reconstructed. The surface reconstruction can be altered or eliminated by deposition of (sub)-monolayer (ML) amounts of a third species, prior to thin film deposition.…”

Section: Introductionmentioning

confidence: 99%

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Influence of interface reconstruction on the formation and superconductive properties of metastable Pb-Ga alloy films

et al. 2011

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We show that the growth, composition, and superconductive properties of ultrathin Pb1−xGax alloy films depend strongly on the atomic structure of the substrate interface. Whereas alloy films on the Si(111)-(7 × 7) surface grow in multilayers, reminiscent of the quantum growth phenomenon observed in pure Pb layers, alloy films on the Si (111)• -Ga interfaces gradually switch to classical layer-by-layer growth. The (7 × 7) interface is unique in that it enables formation of atomically smooth alloy films containing up to 6% of Ga, which is far beyond the solid solubility limit. In contrast, the ( √ 3 × √ 3) interfaces promote phase separation. The contrasting influences of these interfaces are also reflected by their superconductive properties, most notably by the differences in the critical current density, exceeding more than one order of magnitude.

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Chemical Tuning of Metal-Semiconductor Interfaces

Cited by 40 publications

References 29 publications

Quantum Size Effects Induced Novel Properties in Two-Dimensional Electronic Systems: Pb Thin Films on Si(111)

Quantum Size Effects Induced Novel Properties in Two-Dimensional Electronic Systems: Pb Thin Films on Si(111)

Controlling the effective mass of quantum well states in Pb/Si(111) by interface engineering

Influence of interface reconstruction on the formation and superconductive properties of metastable Pb-Ga alloy films

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