Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 3: Preparation and Characterization

HL 3.6: Talk

Monday, March 22, 2010, 11:30–11:45, H14

High temperature dielectric function of Silicon, Germanium and GaN — •Martin Leyer, Markus Pristovsek, and Michael Kneissl — Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin

In the last few years accurate values for the optical properties of silicon, germanium and GaN at high temperatures have become important as a reference for in-situ analysis, e.g. reflectometry. Precise temperature dependent dielectric measurements are necessary for the growth of GaInP/GaInAs/Ge triple-junction solar cells and the hetero epitaxy of GaN on silicon and sapphire.

We performed spectroscopic ellipsometry (SE) measurements of the dielectric function of silicon, germanium and GaN between 1.5 eV and 6.5 eV in the temperature range from 300 K to 1300 K. The Samples were deoxidized chemically or by heating. High resolution SE spectra were taken every 50 K while cooling down to room temperature. The temperature dependence of the critical energies is compared to literature. Measurements for germanium showed a shift of the E₂ critical point of ∼0.1 eV toward lower energies. The reason for this behavior is a non-negligible oxide layer on the samples in the literature.