Umklapp-Mediated Quantization of Electronic States in Ag Films on Ge(111)

Tang, S.-J.; Lee, Y.-R.; Chang, S.-L.; Miller, T.; Chiang, T.‐C.

doi:10.1103/physrevlett.96.216803

Cited by 36 publications

(14 citation statements)

References 28 publications

(23 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both large lattice-mismatched monatomic layers of Ag 2 Ge alloy and 1-ML Pb film on Ag(111) show the common feature of the band splits atM Ag(111) , generated by umklapp scattering via Ag(111). Such substrate-mediated umklapp electronic states in the context of incommensurate interface were observed as a second kind of quantum-well state (QWS) in Ag films [38,39] or Pb films [20] at a thickness above 1 ML on Ge(111). The discrete momentum perpendicular to the surface, k ⊥ , of QWS has to be taken into account for the phase accumulation model although it is the momentum parallel to the surface, k || , which induces umklapp scattering.…”

Section: Resultsmentioning

confidence: 99%

Substrate-mediated umklapp scattering at the incommensurate interface of a monatomic alloy layer

et al. 2019

Self Cite

View full text Add to dashboard Cite

Ultrathin Pb and Ge films deposited on Ag(111) surfaces have been investigated and compared. We found that at 1/3 ML, both films formed surface alloys, Ag 2 Pb and Ag 2 Ge, with √ 3 × √ 3R30 • and 19 20 √ 3 × 19 20 √ 3R30 • structures on Ag(111) but the surface electronic structures exhibit a most evident difference at the Ag(111) surface zone boundaryM Ag(111) , where the single band and the splitting ones were observed, respectively. Up to 1 ML, Ag 2 Ge subsequently develops into germanene with a striped phase and then a quasifreestanding phase, as previously reported [Lin et al., Phys. Rev. Mater. 2, 024003 (2018)], while Ag 2 Pb evolves to a dense Pb(111) phase that also reveals splitting bands atM Ag(111). We discover that the larger (smaller) atomic size of a Pb (Ge) atom with respect to an Ag atom causes the commensurate (incommensurate) interfaces and further demonstrate that the splitting bands of Ag 2 Ge surface alloy and 1-ML Pb film originated from the commonly incommensurate interface with Ag(111), which mediates umklapp scattering by inducing the mirror image of the pristine Ag 2 Ge and Pb(111) bands relative toM Ag(111) .

show abstract

Section: Resultsmentioning

confidence: 99%

Substrate-mediated umklapp scattering at the incommensurate interface of a monatomic alloy layer

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…22,23 The results reported in this Rapid Communication demonstrate that the surface umklapp is important also at organic-metal interfaces: The diffraction of substrate photoelectrons needs to be taken into account when trying to assign genuine interface states. Moreover, evidence is provided that substrate band mapping can be effectively performed through diffraction by an organic molecular adsorbate.…”

Section: Fig 1 (Color Online) Normal Emission Angle-integrated (±7mentioning

confidence: 90%

Final-state diffraction effects in angle-resolved photoemission at an organic-metal interface

et al. 2011

View full text Add to dashboard Cite

In this paper it is shown that angle-resolved photoemission performed using low-energy photons on an organicmetal interface allows to clearly distinguish genuine interface states from features of substrate photoelectrons diffracted by the molecular lattice. As a model system an ordered monolayer of Zn-phthalocyanine is used as a diffraction lattice to probe the electronic band structure of a Ag(110) substrate. Photoemission close to normal emission geometry reveals strongly dispersive features absent in the pristine substrate spectra. Density functional theory modeling helped identifying these as bulk sp direct transitions undergoing surface-umklapp processes. The present results establish the important role of final-state diffraction effects in photoemission experiments at organic-inorganic interfaces. Angle-resolved photoelectron spectroscopy (ARPES) is a preferred tool to study the electronic band structure of single crystals.1 When performed with low photon energy, bulk bandto-band direct transitions may dominate the spectrum.2 Energy and momentum conservation laws allow the band structure to be mapped, for instance, by changing the detection angle and photon energy and by referring to band-structure calculations. This renders the technique to be particularly adapted to probe energy regions relevant for the optical properties of solids. Recently, ARPES was successfully used to investigate the interface properties of conjugated organic nanostructures self-assembled on single-crystal surfaces, which form a new class of materials of steadily growing importance.4-7 ARPES of single-domain structures reveals interface states dispersion, thus enabling access to the electronic properties of twodimensional (2D) systems such as the quasiparticle bandwidth, their effective mass, and correlation effects. 4,5 Alternatively, Fourier-transform analysis of ARPES spectra was recently used to reconstruct the interface molecular orbital densities, including adsorbate-substrate hybridization effects. 6,7 The presence of organic-inorganic hybrid states is not the only aspect relevant to the interpretation of ARPES spectra at interfaces, though. In fact, the adsorption of ordered arrays of atoms 8 or nanostructures 9 on a surface can modify the escape conditions of substrate photoelectrons. The resulting spectra are sensibly affected and reveal the substrate electronic structure via an additional diffraction process often referred to as surface umklapp. 8,9 Within the one-step photoemission model a bulk Bloch wave is optically excited into a damped state extending into the vacuum as a time-reversed lowenergy electron diffraction (LEED) state. 1 The presence of an adsorbate-induced lattice on the substrate crystal surface promotes new LEED states and, consequently, a new set of final states outside the surface. As a result, features observed by ARPES around a given direction may actually originate from bulk direct transitions that are excited one surface reciprocal lattice vector apart.Once deposited on noble-metal substrates, sel...

show abstract

“…Nowadays growing metallic films on semiconductors receives great attention because of the Schottky Barrier at the interface. The Schottky barrier can make a sharp interface between the metallic films and the semiconductor substrates, and also enhance some specific phenomena [1,2]. Furthermore, it is fascinating to grow magnetic thin metal films on semiconductors since it may be employed to design spin-based electronic devices [3,4].…”

Section: Introductionmentioning

confidence: 99%

Coverage-Dependent Cobalt Structure on .RAD.3 * .RAD.3-Ag/Ge(111) Surface

Lin¹,

Tsay

Chen

et al. 2009

e-J. Surf. Sci. Nanotechnol.

View full text Add to dashboard Cite

By using STM, the surface structures of different cobalt coverage grown on √ 3 × √ 3-Ag/Ge(111) surface are investigated. We found that two kinds of structures appear on the cobalt films, one is √ 13 × √ 13 named Structure I, and the other is 2 × 2 named Structure II. Structure I is the structure of the islands with the height under 2 atomic levels, whereas the islands with other heights are Structure II. When the coverage of Co was increased, the transformation of structures reveals a two-stage evolution. The percentage of the Structure II increases rapidly at the coverage of about 1ML and 3 ML. However, the methods for these two elevations are different. The first stage of increasing results from sufficiency of cobalt atoms to form Structure II islands, but the second stage is due to the limitation of cobalt covered areas. The cobalt covered areas reach the limitation of 50% at the coverage of 3.5 ML. Moreover, for the cobalt island of 3.7 nm height, the configuration on the top still exhibits Structure II. This result manifests that large amount of cobalt atoms do not transform into its bulk structure, instead, those cobalt atoms maintain the same structure with the bottom 2 × 2 layers. This coverage-dependent substitution of structures indicates that the transformation of cobalt islands is not due to phase transition. Besides, the exchange between cobalt atoms and the bottom silver layer can also be denied.

show abstract

Umklapp-Mediated Quantization of Electronic States in Ag Films on Ge(111)

Cited by 36 publications

References 28 publications

Substrate-mediated umklapp scattering at the incommensurate interface of a monatomic alloy layer

Substrate-mediated umklapp scattering at the incommensurate interface of a monatomic alloy layer

Final-state diffraction effects in angle-resolved photoemission at an organic-metal interface

Coverage-Dependent Cobalt Structure on .RAD.3 * .RAD.3-Ag/Ge(111) Surface

Contact Info

Product

Resources

About