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Title: Analysis of negative capacitance and self-heating in organic semiconductor devices
Authors : Knapp, Evelyne
Ruhstaller, Beat
Published in : Journal of Applied Physics
Volume(Issue) : 117
Issue : 13
Publisher / Ed. Institution : AIP Publishing
Issue Date: Mar-2015
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Publication)
Language : English
Subjects : Organic semicondutor; Negative capacitance
Subject (DDC) : 621.3: Electrical engineering and electronics
Abstract: In admittance spectroscopy of organic semiconductor devices, negative capacitance values arise at low frequency and high voltages. This study aims at explaining the influence of self-heating on the frequency-dependent capacitance and demonstrates its impact on steady-state and dynamic experiments. Therefore, a one dimensional numerical drift-diffusion model extended by the heat equation is presented. We calculate the admittance with two approaches: a Fourier method that is applied to time domain data and a numerically efficient sinusoidal steady state analysis (S3A), which is based on the linearization of the equations around the operating point. The simulation results coincide well with the experimental findings from reference [H. Okumoto and T. Tsutsui, Appl. Phys. Express 7, 061601 (2014)] where the negative capacitance effect of an organic device becomes weaker with better cooling of the structure. Linking the frequency- and time-domain with the Fourier approach supports an effortless interpretation of the negative capacitance. Namely, we find that negative capacitance originates from self-heating induced current enhancement.
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Publication type: Article in scientific Journal
DOI : 10.1063/1.4916981
ISSN: 0021-8979
Appears in Collections:Publikationen School of Engineering

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