Optical properties of freestanding GaN nanomembranes using monochromated valence-EELS

M. Benaissa, W. Sigle, I. Benabdallah, Rami T. Elafandy, Tien Khee Ng, P.A. van Aken

Research output: Contribution to journalArticlepeer-review

Abstract

In the present study, the dielectric function of freestanding GaN nanomembranes was described using valence electron energy loss spectroscopy coupled to a monochromated electron probe in a Sub-Electron-volt Sub-Angstrom transmission electron Microscope. Such a technique has proven to be very efficient in handling nanometer-scale freestanding nanomembranes and provided local and direct measurements of optical characteristics. Indeed, core-state along with outer-shell electrons transitions were first measured in the configuration where the GaN -axis was normal to the transferred momentum . With the help of Kramers-Kroning analyses and density functional theory, critical points energies were extracted and assigned. Finally, optical data such as the real refractive index n, extinction coefficient k, absorption coefficient α and reflectivity R were numerically deduced from the real and imaginary parts of the dielectric function.
Original languageEnglish (US)
Pages (from-to)115333
JournalMaterials Science and Engineering: B
Volume272
DOIs
StatePublished - Jun 30 2021

ASJC Scopus subject areas

  • Mechanics of Materials
  • Materials Science(all)
  • Mechanical Engineering
  • Condensed Matter Physics

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