CURRENT RESEARCH PROJECTS

Development of a Dynamic Atom Probe

Sponsored by NSF-DMR-MRI #1040456

 

This program's main goal is to integrate an atom probe tomography system with in-situ ultrafast electron diffraction (we affectionately refer to this system as the Ritatron).  Ultimately, the system was proven to integrate atomic spatial and chemical resolution measurements with sub-ns temporal resolution for monitoring diffusion, phase transformations, and crystallization processes.  Check out our publication in JMR: https://doi.org/10.1557/jmr.2015.86

 

Gorman's group has been instrumental in the development of hardware and techniques cross-correlative STEM and APT since 2006.  The combination allows for APT reconstruction accuracy improvements as well as direct measurements of electrical property / atomic structure correlations.

 

These days, we are using the Ritatron for in-situ TEM / electron diffraction / electron ptychography experiments in order to improve APT data reconstruction methods.  Check out the Facilities section for more pics and info about the instrument.

 

Atomic Scale Characterization of Photovoltaic Devices

Sponsored by and in collaboration with NREL

 

Atomic scale characterization of photovoltaics using a combination of atom probe tomography and electron microscopy / spectroscopy allows us to determine the elemental causes of efficiency limiters.  Our group currently has focus areas in multicrystalline Si, epitaxial Si, amorphous Si, CdTe, and III-V heterostructures.

 

Technique developments include cross-correlative EBIC and cathodoluminescence along with APT for a direct correlation between atomic scale defect structure and its electrical properties.

 

Adam recently showed that measurement of the defect chemistry at interfaces and grain boundaries in CIGS allows us to derive the electrical properties of interfaces DIRECTLY from APT data.

 

Atomic Scale Characterization of Oxides

 

Atomic scale understanding of interfaces in oxides, especially those used for electronic devices, enables a direct correlation between atomic structure and electronic or ionic transport.  Internal interfaces can include grain boundaries, epitaxial interfaces for 2D electron gases, and metal / dielectric interfaces.  Publication links: CeO2, BCZY, CIGS

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