Related docs:
Research Interests
Surface chemistry projects
Presentations:
2nd Y Oral Presentation (pdf, 5MB)
226 ACS presentation (pdf, 2.8MB)
Avances en Electronica Molecular, Mexico Nov '03 (pdf, 25 MB)
Progres Recents dans L'Electronique Moleculaire, Paris Dec '03 (pdf, 33 MB)
From grad school:
More information about my main research and previous research
-----------------Surface Chemistry and Interphase Characterization
I was involved in other two current research activities:
Organic Functionalization of Semiconductors and Metal Surfaces pre-print (pdf, 564KB)
This is perhaps one of the most important and feasible approaches to surpass current challenges and boundaries of the gold-thiol system in a self-assembled monolayer (SAM), needed for typical electronic testbeds and nanodevices. We capitalize on the high reactivity of a new alligator clip that we incorporated in our normal OPEs, based on diazonium salts (DS). We have achieved molecular grafting of simple and binary semiconductors like Si and GaAs, as well as transition metals like Pd, using new DS with no need of external activation. Although the use of other small aromatic DS have been used in the past for the same purpose, our new methodology stands for an easy, clean and fast reaction of the OPE-DS toward differente surfaces.
I was directly responsible for the synthesis of new OPE-DS that are air-stable, with a high solubility, and reactivity toward materials of interest. These new OPE-DS also have functional groups that enhances spectroscopic characterization. The analysis of the functionalized surface has been done using FTIR, CV, XPS, AFM and STM.
This approach is based on several new features that require a full characterization before combining them together. The current stage of this project is the of electrical testings of at least two different silicon-hybrid electronic devices. The first device is a nanopore comprising an etched area in the scale of hundreds of microns that is H-passivated after a shadow-mask lithography step. The process is a collaboration work with Prof. Mark Reed's group. This nanopore is then molecular grafted with the desire OPE-DS and finally the top metallic layer as 2nd electrode is evaporated, for further electrical measurements.The second Si-hybrid device is a smaller area than the nanopore, based on poly-Si and SiON, prepared by E-beam lithography, characterized by scanning electron microscopy (SEM) and high-resolution tunneling electron microscopy (HRTEM), in collaboration with Sandia Labs. The chip has a gate oxide to be etched of ca. 2nm, for a subsequent molecular assembly using OPEs-DS that matches the gate oxide opening.
Si-hybrid testbeds are seen as the natural evolution of molecular electronic devices, where molecular thin layers form part of technologically important materials like Si, which is widely used for integrated circuit technology
Selective Functionalization of Carbon Nanotubes with Diazonium Salts pre-print (pdf, 260KB)
I recently started studying the selective reaction of DS over single-walled carbon nanotubes (SWNT). The preparation of SWNT yields always a mixture of different electronic types, mainly metallic and semiconductor; and this polydispersion is the principal limitation for the SWNT to find a wide applicability based on their unique electronic properties.
DS functionalize selectively SWNT, allowing the control of the reaction pathway for a good separation of the different electronic species. We have observed that the functionalization of metallic SWNT is reversible, so the material of interest goes under reaction, separation and recovered. Although this selectivity has been well proved, the reaction mechanism and analysis of functionalization is still under progress. In this project i was responsible for the synthesis small aromatic DS that can selectively react with the metallic SWNT. We are also devolping a methodology to analyze the chemical species of the products by using gas chromatography-mass spectroscopy (GC-MS), UV-Vis and Raman spectroscopy, as well as XPS.
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More information about my main projects and my previous research