Dresden 2006 – scientific programme
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DS: Dünne Schichten
DS 8: Functional thin films I
DS 8.2: Talk
Tuesday, March 28, 2006, 10:15–10:30, GER 37
ELS to determine the band gap of thin dielectric layers — •Matthias Bergholz, Rakesh Sohal, and Dieter Schmeißer — Brandenburgische Technische Universität Cottbus, Angewandte Physik-Sensorik, Konrad-Wachsmann-Allee 17, 03046 Cottbus
In ultra thin layers of high-K materials the value of the band gap can be derived not explicitly although it is a key quantity in the electric behavior. We use ELS with a monochromatized (50 meV - 150 meV) electron gun and primary energies between 20 eV and 30 eV. Starting with the native SiO2/Si(001) layers we find that loss function of the substrate dominates for using primary energies beyond 50 eV. In contrast at energies below 50 eV the loss intensity can be used to derived the band gap with an accuracy of ±200 meV. We compare thin (<3 nm) films of HfOx, Pr2O3, Al2O3 and Si-Oxynitrides and discuss the band gap values as well as the scattered intensity observed within the gap.