Topic
Scanning tunneling spectroscopy
About: Scanning tunneling spectroscopy is a research topic. Over the lifetime, 7886 publications have been published within this topic receiving 213828 citations.
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TL;DR: In this article, the quantum-confinement effects in Ge nanocrystals formed with ultrahigh density (>1012cm−2) by Ge deposition on ultrathin Si oxide films were revealed.
Abstract: Scanning tunneling spectroscopic studies revealed the quantum-confinement effects in Ge nanocrystals formed with ultrahigh density (>1012cm−2) by Ge deposition on ultrathin Si oxide films. With decreasing crystal size, the conduction band maximum upshifted and the valence band minimum downshifted. The energy shift in both cases was about 0.7 eV with the size change from 7 to 2 nm. This shows that the energy band gaps of Ge nanocrystals increased to ∼1.4eV with decreasing size. This size dependence can be explained by the quantum-confinement effect in Ge nanocrystals.
113 citations
TL;DR: In this paper, the authors describe the design and development of a scanning tunneling micoscope (STM) working at very low temperatures in ultra-high vacuum (UHV) and at high magnetic fields.
Abstract: We describe the design and development of a scanning tunneling micoscope (STM) working at very low temperatures in ultra-high vacuum (UHV) and at high magnetic fields. The STM is mounted to the 3He pot of an entirely UHV compatible 3He refrigerator inside a tube which can be baked out to achieve UHV conditions even at room temperature. A base temperature of 315 mK with a hold time of 30 h without any recondensing or refilling of cryogenics is achieved. The STM can be moved from the cryostat into a lower UHV-chamber system where STM-tips and -samples can be exchanged without breaking UHV. The chambers contain standard surface science tools for preparation and characterization of tips and samples in particular for spin-resolved scanning tunneling spectroscopy (STS). Test measurements using either superconducting tips or samples show that the system is adequate for performing STS with both high spatial and high energy resolution. The vertical stability of the tunnel junction is shown to be 5 pmpp and the energy resolution is about 100 μeV.
113 citations
TL;DR: In this article, the electron-phonon coupling is treated as a quantum coherent process, in the sense that no random dephasing is introduced in the scattering wave functions.
Abstract: We present a technique to calculate the transport properties through one-dimensional models of molecular wires The calculations include inelastic electron scattering due to electron-lattice interaction The coupling between the electron and the lattice is crucial to determine the transport properties in one-dimensional systems subject to Peierls transition since it drives the transition itself The electron-phonon coupling is treated as a quantum coherent process, in the sense that no random dephasing due to electron-phonon interactions is introduced in the scattering wave functions We show that charge-carrier injection, even in the tunneling regime, induces lattice distortions localized around the tunneling electron The transport in the molecular wire is due to polaronlike propagation We show typical examples of the lattice distortions induced by charge injection into the wire In the tunneling regime, the electron transmission is strongly enhanced in comparison with the case of elastic scattering through the undistorted molecular wire We also show that although lattice fluctuations modify the electron transmission through the wire, the modifications are qualitatively different from those obtained by the quantum electron-phonon inelastic scattering technique Our results should hold in principle for other one-dimensional atomic-scale wires subject to Peierls transitions
112 citations
TL;DR: Topographies of different edge structures of monolayer graphene show that the localization of the electronic density of states along the C-C bonds results in quantum interference patterns along the graphene carbon bond network, whose shapes depend only on the edge structure and not on the electron energy.
Abstract: Electron scattering at graphene edges is expected to make a crucial contribution to the electron transport in graphene nanodevices by producing quantum interferences. Atomic-scale scanning tunneling microscopy (STM) topographies of different edge structures of monolayer graphene show that the localization of the electronic density of states along the C-C bonds, a property unique to monolayer graphene, results in quantum interference patterns along the graphene carbon bond network, whose shapes depend only on the edge structure and not on the electron energy.
112 citations
TL;DR: From scanning tunneling microscopy and spectroscopy experiments it is shown that control over the charge-state of individual molecules adsorbed on surfaces can be obtained by choosing a substrate system with an appropriate workfunction.
Abstract: From scanning tunneling microscopy and spectroscopy experiments it is shown that control over the charge-state of individual molecules adsorbed on surfaces can be obtained by choosing a substrate system with an appropriate workfunction. The distribution of the additional charge is studied using difference images. These images show marked intramolecular contrast.
112 citations