Electron hopping at the Si(111):B-root 3 surface: Insight from local impurity spectroscopy

Cédric Tournier-Colletta
American Physical Society, 2013
Journal paper

Abstract

Boron vacancies at the Si( 111):B-root 3 surface are model systems in the comprehension of strongly correlated semiconductor surfaces. By using scanning tunneling spectroscopy, the origin of the single-vacancy electronic structure is addressed. It is shown to originate from the localization of a well-identified dangling-bond surface state with significant B character. The bivacancy defect, which is characterized by energy-split bonding and antibonding states, is interpreted within the textbook diatomic molecule picture. From the hopping parameter, we determine the bandwidth of the surface state from which the impurity state derives and evaluate the strength of many-body effects. Our analysis supports the realization of the Mott-Hubbard insulator state in half-filled dangling-bond surface states on root 3-reconstructed surfaces, as proposed recently for SiC(0001), Sn/Ge(111), and Sn/Si(111). DOI: 10.1103/PhysRevB.87.075427

Official source

https://infoscience.epfl.ch/record/185347?ln=en

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts

Related publications

Related publications (3)

This thesis reports measurements at the single atom scale by using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Different sample systems where analyzed with normal conducting and superconducting tips. Chapter 2 presents the theoretical aspects which have to be taken into account for a detailed analysis and a consistent interpretation of the STS measurements. In chapter 3 the creation of a hexagonally ordered superlattice of single Ce adatoms on Ag(111) is reported and understood within a scattering model of the surface state electrons with the adatoms. Furthermore, the change in the local density of states of the surface state in ordered and slightly disordered superlattices is measured and theoretically explained within a tight-binding model which allows to understand the creation and stability of the superlattice by an energy gain of the participating surface-state electrons. Because Ce atoms have a non-vanishing magnetic moment which is expected to interact with the continuous states of the supporting surface leading to a Kondo resonance, chapter 4 presents measurements on single Ce adatoms on different Ag surfaces. This chapter shows the difficulties to interpret the obtained data. For instance, bistable Ce adatoms are detected on Ag(100) which show drastical changes in their apparent height and spectral signature depending on the tunneling conditions. The possible physical processes behind these phenomena are discussed. While the results presented in the first chapters were obtained with a normal conducting tip, chapter 5 intensively discusses the opportunities superconducting tips offer in low-temperature STS measurements. Novel insight in and thorough understanding of Andreev reflection processes are obtained by using the unique possibility of having different superconducting gaps in the tip and the sample. Detailed analyses of the supercurrent at low tunneling resistances reveal tunneling currents which are not described within the standard resistivity shunted junction model, and are presumably due to self-induced tunneling or due to an additional quasiparticle tunneling channel which only exist in asymmetric junctions. Furthermore, the influence of single magnetic Co atoms inbetween the superconducting tunnel junction on the obtained spectrum is discussed.

EPFL2006

Decay mechanisms of excited electrons in quantum-well states of ultrathin Pb islands grown on Si(111): Scanning tunneling spectroscopy and theory

I-Po Hong, François Patthey, Wolf-Dieter Schneider

Using low-temperature scanning tunneling spectroscopy at 5 and 50 K, we studied the linewidth of unoccupied quantum-well states in ultrathin Pb islands, grown on Si(111) on two different Pb/Si interfaces. A quantitative analysis of the differential conductance spectra allowed us to determine the electron-electron (e-e), electron-phonon (e-ph) and the interface and defect contributions to the lifetime. Layer-dependent ab initio calculations of the e-ph linewidth contribution are in excellent agreement with the data. Importantly, the sum of the calculated e-e and e-ph lifetime broadening follows the experimentally observed quadratic energy dependence.

2009

Single-Molecule Vibrational Spectroscopy of H2O on Anatase TiO2(101)

Christian Alexander Stephan Dette, Feliciano Giustino, Klaus Kern, Shai Mangel

Atomic level understanding of water on titanium dioxide (TiO2), in particular the mineral form anatase, is exceptionally important, considering its practical applications including photocatalytic water-splitting, photoinduced hydrophilicity , and water purification.(1-3) Although much effort has been devoted to the study of water adsorption and dissociation on anatase, investigating the fundamental steps of single water splitting remains challenging. These challenges arise from the difficulty of chemical identification of single molecular water and its dissociation products. Here, we have unequivocally identified single water molecules and hydroxyls on the TiO2 anatase (101) surface using scanning tunneling microscopy (STM) in combination with inelastic tunneling spectroscopy (IETS). Labeling of single molecules on the semiconductor surface was confirmed by demonstrating the isotope shift of the vibrational signatures and by first-principles density functional theory (DFT). The chemical identification of individual water molecules on anatase opens a direct path to follow the water splitting process on the single molecule level.

American Chemical Society2017

EPFL2006