Electron‐Energy‐Loss Spectroscopy of Different Al2O3 Modifications. I. Energy Loss Function, Dielectric Function, Oscillator Strength Sum Rule and the Quantity ϵ2E

Abstract

AbstractUsing 40 keV electrons electron‐energy‐loss measurements are performed on amorphous, polycrystalline γ‐ and α‐Al2O3 thin films. From the electron‐energy‐loss spectra measured in the energy range up to 40 eV the energy‐dependent energy loss function Im(–ϵ−1) is derived. The dielectric function, optical constants, and neff(E) are computed using the Kramers‐Kronig analysis and wellknown formulae. The quantity ϵ2E is compared with a simple joint density of states model.