Berlin 2015 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 6: Poster Session DF

DF 6.1: Poster

Montag, 16. März 2015, 19:00–21:00, Poster C

Analysis of immittance spectra: unambiguous electrical equivalent circuits representing the underlying physics — •Julian Alexander Amani, Tristan Koppe, Hans Hofsäss, and Ulrich Vetter — II. Physikalisches Institut der Georg-August-Universität Göttingen, Deutschland

We propose an approach of analysing immittance spectra with electrical equivalent circuits, which not only eliminates circuit ambiguity but also directly extracts the parameters of the selected physical models.

Analysis of immitance spectra is usually performed by optimising the values of idealised, lumped components in an electrical equivalent circuit to fit the measured data. Those circuits consisting only of idealised components are known to be ambiguous, i. e. different arrangements of components fit the measured data equally well. Hence, definite association of circuit components with physical parts of the system is not possible.

To find the arrangement representing the underlying physics correctly, we derived a fundamental electrical equivalent circuit from Maxwell's equations, describing a homogeneous piece of material, that allows non-linear components dependent on external parameters. In the resulting Voigt circuit, actual physical models are used as resistive and a complex capacitive components. Using measurements of a heterostructure as example we show how, with variation of external parameters (e. g. bias voltage), the unambiguous circuit can be used to extract parameters of the model (e. g. Schottky barrier height) instead of single values of resistance and capacitance.