High-Resolution Analog of Time-Domain Phonon Spectroscopy in the TEM Experimental Data and Analysis 2019-2020



The behavior of coherent acoustic phonons (CAPs) as they propagate through a material is a function of the material’s optoelectronic and structural properties, making these collective oscillations a multi-faceted characterization tool. While CAPs are usually detected using transient reflectivity measurements, they have also previously been observed directly in real space using ultrafast electron microscopy (UEM). Here, we report use of UEM to measure localized CAP behavior in an amorphized and annealed GaAs specimen, and demonstrate the sensitivity of this measurement to atomic structure changes. The velocities are compared to expected values for speed of sound in order to draw conclusions about the degree of crystallinity of the specimen pre- and post-annealing. The ability to use a real-space technique to observe CAP behavior with high spatial resolution opens the door to measurements of spatially heterogeneous structural and optoelectronic properties. The data acquired in this experiment as well as analysis code are released here to enable open access to published data.

Data files are included in three categories: Raw UEM data files generated by the Gatan camera attached to the electron microscope in Amundson Hall B47 in .dm3 format, renamed with timestamps assigned in filenames for clarity, analysis code in .m (Matlab) format, and analysis results in .opj (Origin) and .xls format. Documentation of the code is included in the subfolder labeled "Analysis Code." All references to figures refer to "VandenBussche, E. J., Flannigan, D.J.; High-Resolution Analog of Time-Domain Phonon Spectroscopy in the TEM. (submitted)"
Date made availableMay 12 2020
PublisherData Repository for the University of Minnesota
Date of data productionMay 13 2019

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