Correlated electron tunneling in the single-molecule nanosystems

The original approach to the creation of high-temperature single-electron tunneling systems has been developed based on the use of nanocluster molecules. The morphology and electron tunneling characteristics through single nanocluster molecules organized as highly-ordered monolayer Langmuir-Blodgett films on atomically-flat graphite substrate have been studied experimentally using scanning tunneling microscopy (STM) and spectroscopy techniques with sub-nanometer spatial resolution in a double barrier tunnel junction configuration "STM" tip - monomolecular film - conducting substrate" at ambient conditions. Molecular single-electron transistors on the basis of a single nanocluster molecule operating at room temperature were constructed and studied. Various nanocluster molecules with cores from 3 to 23 metal atoms were used as a central electrode in these transistors. Computer simulation of I-V curves of molecular single-electron tunneling (SET) transistor was carried out using the modified theory of single-electronics with consideration of discreteness of the energy spectrum of a molecule as well as the effects of energy relaxation of electrons in the molecule. A comparison of the simulated I-V curves with the experimental ones allow to conclude that the experimental data correspond to the slow energy relaxation case

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign

Molecular cluster based nanoelectronics

The use of molecular clusters as a basis of molecular single-electronic systems is considered experimentally and theoretically. The Langmuir-Blodgett formation and scanning tunneling microscope study of structures with chemically different cluster molecules is described. I-V curves and control curves of molecular single-electron transistors based on various single molecules were studied at room temperature. Comparison of experimental I-V curves with simulated ones allows us to identify a regime of slow energy relaxation of electrons in experimental transistors. Experimental study of electron transport through the planar molecular nanosystems has shown a correlated character of electron tunneling in such systems. (C) 2003 Elsevier B.V. All rights reserved