Tunneling mechanisms in electrochemical STM —distance and voltage tunneling spectroscopy

Halbritter, J.; Repphun, G.; Vinzelberg, Stefan; Staikov, G.; Lorenz, W.J.

doi:10.1016/0013-4686(95)00038-g

Cited by 102 publications

(97 citation statements)

References 24 publications

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“…This value is in the typical range where tunneling is measured 42 (see the Appendix). The relative dielectric constant of the oxide has been set to 3.9, while the oxide effective mass of electrons and holes has been set to 0.40 m e and 0.32 m e , respectively, 43 m e being the free electron mass.…”

Section: Transport Calculation Detailsmentioning

confidence: 82%

Silicon quantum dots embedded in a SiO2matrix: From structural study to carrier transport properties

et al. 2013

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We study the details of electronic transport related to the atomistic structure of silicon quantum dots embedded in a silicon dioxide matrix using ab initio calculations of the density of states. Several structural and composition features of quantum dots (QDs), such as diameter and amorphization level, are studied and correlated with transport under transfer Hamiltonian formalism. The current is strongly dependent on the QD density of states and on the conduction gap, both dependent on the dot diameter. In particular, as size increases, the available states inside the QD increase, while the QD band gap decreases due to relaxation of quantum confinement. Both effects contribute to increasing the current with the dot size. Besides, valence band offset between the band edges of the QD and the silica, and conduction band offset in a minor grade, increases with the QD diameter up to the theoretical value corresponding to planar heterostructures, thus decreasing the tunneling transmission probability and hence the total current. We discuss the influence of these parameters on electron and hole transport, evidencing a correlation between the electron (hole) barrier value and the electron (hole) current, and obtaining a general enhancement of the electron (hole) transport for larger (smaller) QD. Finally, we show that crystalline and amorphous structures exhibit enhanced probability of hole and electron current, respectively.

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Section: Transport Calculation Detailsmentioning

confidence: 82%

Silicon quantum dots embedded in a SiO2matrix: From structural study to carrier transport properties

et al. 2013

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“…This effect can be detected with the distance tunneling spectroscopy (DTS) method by measuring the contact conductance as a function of the gap z between the electrodes [18]. The first experiments related to DTS were done on physically adsorbed He [19] and the deviation of the tunnel conductance ( ) G z from exponential behavior was attributed to the strong reduction of the electron density of states close to the Fermi level by adsorbed atoms of helium predicted by Lang [20].…”

Section: Introductionmentioning

confidence: 99%

Electron scattering effects at physisorbed hydrogen molecules on break-junction electrodes and nanowires formation in hydrogen environment

Maas

Vasnyov

Hendriksen

et al. 2012

Low Temperature Physics

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The physisorption of hydrogen molecules on the surface of gold and other coinage metals was studied using distance tunneling spectroscopy. We observed strong N-shaped deviation of the tunnel current (resistance) vs distance dependences from the exponential one. Such deviations are difficult to explain in the framework of the Tersoff-Hamann approximation. We suggest the scattering of the tunneling electrons by H 2 molecules as origin for observed effect. We found that this phenomenon is also common for strongly adsorbed organic molecules with one anchoring group. Pulling Au, Cu and Pt nanowires at 22 K in hydrogen environment show that the electrodes of break junctions are still connected up to very low conductances of 10 -4 -10 -6 G 0 through hydrogen-metal one-atom chains.

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“…As a result, the tunnel barrier height is about 1 eV to 2 eV, lower than in vacuum [126]. According to Equation (3.10) in the electrochemical environment an effective reduced tunnel barrier height φ M,eff < φ M,UHV results [14,53,75,76,77,85,142,153,159,169,176,193].…”

Section: Setup Of the Ec-stmmentioning

confidence: 99%

“…The oscillation amplitude was measured to be ±0.8 eV around the mean tunnel barrier height φ eff = 1.51 eV [93]. The effective reduced tunnel barrier height results from tunneling via intermediate states [77,153] and calculations show that tunneling via hydrogen atoms results in a potential barrier in the range of measured values [13,58,170].…”

Section: Setup Of the Ec-stmmentioning

confidence: 99%

Spin-polarized scanning tunneling microscopy at the solid/liquid interface

Majer

Schindler

2015

Surface Science

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The spin-polarized scanning tunneling microscopy (sp-STM) is demonstrated between a magnetized STM tip and a magnetic substrate at the solid/liquid interface under electrochemical conditions at room temperature. Thereby, sp-STM at the solid/liquid interface is accomplished using the differential magnetic mode established by Wulfhekel and Kirschner for investigations at the solid/vacuum interface. The implementation of the sp-STM setup into the electrochemical STM is an important part of this thesis. Special attention is paid to the magnetostriction effect of possible magnetic STM tips. As a model system extended Co islands are electrochemically grown on an Au(111) single crystal. An appropriate electrochemical environment is required to ensure metal Co islands on Au(111), since Co deposition occurs at low potentials where hydrogen evolution and dissolved oxygen contributes to electrochemical reactions at the substrate. After sample preparation extended Co islands on Au(111) up to four atomic layers in height are observed with bare Au(111) areas in between, which is an ideal sample surface for sp-STM at the solid/liquid interface showing ferromagnetic and diamagnetic areas. Sp-STM is employed in-situ at the solid/liquid interface to observe not only sample topography but also sample magnetization of the model system Co/Au (111)

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Tunneling mechanisms in electrochemical STM —distance and voltage tunneling spectroscopy

Cited by 102 publications

References 24 publications

Silicon quantum dots embedded in a SiO2matrix: From structural study to carrier transport properties

Silicon quantum dots embedded in a SiO2matrix: From structural study to carrier transport properties

Electron scattering effects at physisorbed hydrogen molecules on break-junction electrodes and nanowires formation in hydrogen environment

Spin-polarized scanning tunneling microscopy at the solid/liquid interface

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