Current Search:   Rodriguez Garrigues, Alvar (x)

View All Items

  • CSV Spreadsheet
(1 - 2 of 2)
Development of an Efficient Molecular Single-Electron Transport Spectroscopy
Title
Development of an Efficient Molecular Single-Electron Transport Spectroscopy.
Creator
Rodriguez Garrigues, Alvar, Gonzalez Garcia, Enrique, Flitsiyan, Elena, Ishigami, Marsahir, University of Central Florida
Abstract / Description
In this thesis I present a complete and detailed guide for the development process and fabrication of efficient single-electron transistors (SETs) and a better single-molecule magnets (SMMs) deposition yield. Starting from a commercial Si/SiO2 wafer I show the steps for the deposition of different layers to fabricate a SET as well as the improvements achieved in those for a completely functional SET device. The development process is based on a combination of optical lithography and e-beam...
Show moreIn this thesis I present a complete and detailed guide for the development process and fabrication of efficient single-electron transistors (SETs) and a better single-molecule magnets (SMMs) deposition yield. Starting from a commercial Si/SiO2 wafer I show the steps for the deposition of different layers to fabricate a SET as well as the improvements achieved in those for a completely functional SET device. The development process is based on a combination of optical lithography and e-beam lithography with metal deposition in ultra-high vacuum. The improvements involve a better conductance in the Al gate component, with a controlled formation of the superficial oxide layer and a faster feedback electromigration-induced breaking of Au nanowires for the creation of nanogaps at room temperature. The gate component is improved by increasing its thickness and exposing it to plasma oxidation for the complete oxidation of its surface. The nanowire breaking is realized at room temperature to make use of the surface tension of Au, which, after a previous feedback procedure, eventually opens the final gap in the nanowire. Finally, I demonstrate a new technique that allows increasing the yield of having a SMM connected in the nanowire gap. This new technique is based on monitoring the resistance of the broken nanowires during the SMM deposition from a controlled liquid solution at room temperature. When the resistance ((>)G? for open gaps) drops to values below Mega-ohms (characteristic resistance of a molecule bridging the gap) for a number of nanowires in the chip, the device is then ready for low temperature measurements.
Show less
Date Issued
2013
Identifier
CFE0004742, ucf:49775
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004742
Electrostatic control over temperature-dependent tunneling across single-molecule junctions
Title
Electrostatic control over temperature-dependent tunneling across single-molecule junctions.
Creator
Rodriguez Garrigues, Alvar, Del Barco, Enrique, Flitsiyan, Elena, Ishigami, Masa, Hernandez, Eloy, University of Central Florida
Abstract / Description
The aim of the present dissertation is to improve the understanding and methodology of temperature-dependent tunnel conduction through individual molecules by single-electron transport spectroscopy. New advances in electrochemistry present individual molecular diodes as a realistic option for the implementation on molecular circuits thanks to their high current rectification ratios. Therefore, a major requisite in this field is to understand and control the conduction behaviors for a large...
Show moreThe aim of the present dissertation is to improve the understanding and methodology of temperature-dependent tunnel conduction through individual molecules by single-electron transport spectroscopy. New advances in electrochemistry present individual molecular diodes as a realistic option for the implementation on molecular circuits thanks to their high current rectification ratios. Therefore, a major requisite in this field is to understand and control the conduction behaviors for a large variety of conditions. This work focuses on the electric conduction through ferrocene-based molecules as a function of temperatures within a wide range of bias and gate voltages by means of three-terminal electromigrated-broken single-electron transistors (SETs).The results show that the temperature dependence of the current (from 80 to 260 K) depends strongly on the bias and gate voltages, with areas in where the current increases exponentially with temperature (at the Coulomb blockade regimes), and others where the increase of the temperature makes the current only to vary slightly (at resonance) or to decrease monotonically (at the charge degeneracy points). These different observed behaviors of the tunneling current with increasing temperatures can be well explained by a formal single-level coherent tunneling model where the temperature dependence relies on the thermal broadening of the Fermi distributions of the electrons in the leads. The model portraits the molecule as a localized electrostatic level capacitively coupled to the transistor leads, and the electrical conduction through the junction as coherent sequential tunneling.
Show less
Date Issued
2016
Identifier
CFE0006171, ucf:51132
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006171