Colloidal Nanocrystal Routes to Inorganic Nanocomposite Thermoelectric Materials

Project: Research project

Description

The scientific goal of this project is to make in-situ measurements of the resistivity of nanowire (NW) structures of sub-10nm size using an Ultra-High Vacuum Scanning Tunneling Microscope (UHV-STM). The structures of primary interest are endotaxial silicide NWs, which are perfect, single-crystal structures with atomically flat facets, both at the vacuum interface and at the buried metal-semiconductor interface. These NWs can have widths as small as a few nm and lengths exceeding 1 micron. A variable-distance two-point configuration will be used to alleviate effects of contact resistance. Resistivity increase due to boundary scattering will be modeled with the Fuchs-Sondheimer relation. The presence of perfect boundaries at the NW interfaces suggests that size effects will be minimal, even for NW dimensions smaller than the bulk scattering length (typically 40 nm). This hypothesis will be explored using variable width, variable temperature and partial oxidation of the NW structures. A secondary goal of the project is to develop the techniques for resistance measurement of nano-structures using UHV in situ probes. This will require a controlled approach for the contact, control of possible leakage currents and understanding of point-contacts in general. The use of well-defined prototype structures with controllable size and perfect interfaces, combined with in situ UHV methods will allow the various effects to be isolated in a controlled fashion and with extreme values. Outcomes of this project will include: improved understanding of transport in nanoscale contacts and metallic conductors at extreme limits; advancement of experimental methods and theoretical understanding of in situ nano-probe measurements. An important goal of this project is the integration of research, education and teaching, which is epitomized in the training of graduate and undergraduate students and the incorporation of frontier research topics into the classroom and beyond. This project will be administered with full participation of students, both graduate and undergraduate, who will design, build and operate their own equipment. Nanoscale imaging and electrical measurements are well suited for public outreach, having visual appeal and intuitive simplicity. Outreach for this project will be integrated with the Science is Fun program in the Leroy Eyring Center for Solid State Science at ASU. More formal efforts will be coordinated with the Down-to-Earth Science (DES) program, an NSF-funded GK-12 track II project at ASU (http://gk12.asu.edu). Students will learn how to communicate their research to a broader audience and how to translate the core concepts and findings from their research into valuable inquiry-based lessons/activities that are aligned with the Arizona (as well as the national) science standards.
StatusFinished
Effective start/end date8/1/157/31/18

Funding

  • NSF-MPS: Division of Materials Research (DMR): $425,000.00

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thermoelectric materials
nanocomposites
nanocrystals
routes
nanowires
students
education
Earth sciences
electrical resistivity
probes
in situ measurement
contact resistance
scattering
electrical measurement
ultrahigh vacuum
flat surfaces
leakage
conductors
microscopes
prototypes