Probing collective oscillation of -orbital electrons at the nanoscale
arXiv:1708.03817 · doi:10.1063/1.5012742
Abstract
Here we demonstrate that high energy electrons can be used to explore the collective oscillation of , , and orbital electrons at the nanometer length scale. Using epitaxial AlGaN/AlN quantum wells as a test system, we observe the emergence of additional features in the loss spectrum with increasing Ga content. A comparison of the observed spectra with ab--initio theory reveals the origin of these spectral features is attributed to 3--electrons contributed by Ga. We find that these modes differ in energy from the valence electron plasmons in AlGaN due to the different polarizability of the electrons. Finally, we study the dependence of observed plasmon modes on Ga content, lending insight into plasmon coupling with electron--hole excitations.