Ludvig de Knoop, Hanna Nilsson, Andrew Yankovich, Norvik Voskanian, Lunjie Zeng and Eva Olsson
Department of Physics, Chalmers University of Technology, 412 96 Gothenburg, Sweden
Transport of matter and charges as well as heat spread properties are determined by the fine scale microstructure. In situ electron microscopy enables experiments where the local properties can be directly correlated to material structure using specimen holders that are designed to enable different stimuli. We can study, for example, electric field and thermal induced changes of charge and matter transport properties and mechanisms. The direct correlation on the small scale involving individual interfaces, defects and atoms provides access to new information about which microstructural constituents that are active in determining the material properties on the macro, micro, nano and atomic scale. This talk addresses examples of in situ electrical and thermal studies.
Heating of a transmission electron microscopy (TEM) specimen can be performed in several parallel modes and this talk will address three types of heating modes and show experimental results from nanostructured materials. One mode is by resistive heating of a ring shaped support in contact with the circumference of the entire TEM sample. An additional mode is by use of a heating wire patterned on the TEM sample where the wire is contacted by leads fed through the TEM sample holder. The third mode is by active Joule heating of the nanostructure of study, such as carbon nanotubes, graphene, or metal nanowires. The purpose of having several parallel modes of heating is to enable the separation of temperature dependence, effects of self-Joule heating, effects of radiative heating and thermal transport. It is also important to be able to extract the three dimensional information about the geometry of the investigated structures.
The talk will also address electrical transport and coupling mechanisms, for example, reduced graphene oxide, metallic oligomers and nanowires. The electrical probing is performed using an in situ probe that is positioned with a sub-Ångström precision in the x-, y- and z-direction. Further functionalities are provided by patterning electrodes on the specimen. Different effects induced by electric fields will be presented.
