Kavli Affiliate: Scott K. Cushing
| First 5 Authors: Levi D. Palmer, Wonseok Lee, Daniel B. Durham, Javier Fajardo, Jr., Yuzi Liu
| Summary:
Measuring nanoscale local temperatures, particularly in vertically integrated
and multi-component systems, remains challenging. Spectroscopic techniques like
X-ray absorption and core-loss electron energy-loss spectroscopy (EELS) are
sensitive to lattice temperature, but understanding thermal effects is
nontrivial. This work explores the potential for nanoscale and element-specific
core-loss thermometry by comparing the Si L2,3 edge’s temperature-dependent
redshift against plasmon energy expansion thermometry (PEET) in a scanning TEM.
Using density functional theory (DFT), time-dependent DFT, and the
Bethe-Salpeter equation, we ab initio model both the Si L2,3 and plasmon
redshift. We find that the core-loss redshift occurs due to bandgap reduction
from electron-phonon renormalization. Our results indicate that despite lower
core-loss signal intensity compared to plasmon features, core-loss thermometry
has key advantages and can be more accurate through standard spectral
denoising. Specifically, we show that the Varshni equation easily interprets
the core-loss redshift for semiconductors, which avoids plasmon spectral
convolution for PEET in complex junctions and interfaces. We also find that
core-loss thermometry is more accurate than PEET at modeling thermal lattice
expansion in semiconductors, unless the specimen’s temperature-dependent
dielectric properties are fully characterized. Furthermore, core-loss
thermometry has the potential to measure nanoscale heating in multi-component
materials and stacked interfaces with elemental specificity at length scales
smaller than the plasmon’s wavefunction.
| Search Query: ArXiv Query: search_query=au:”Scott K. Cushing”&id_list=&start=0&max_results=3