Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 77: Organic Electronics and Photovoltaics - Transport and Doping
CPP 77.4: Vortrag
Freitag, 16. März 2018, 10:30–10:45, C 243
Measuring the Lateral Charge-Carrier Mobility in Metal-Insulator-Semiconductor Capacitors via Kelvin-Probe — •Karl-Philipp Strunk1, Valeria Milotti1, Alexander Ullrich2, and Christian Melzer1 — 1Centre for Advanced Materials, University of Heidelberg, Germany — 2Organisch-Chemisches Institut, University of Heidelberg, Germany
DC current-voltage measurements on organic field-effect transistors are commonly used to characterize the planar electrical transport in organic semiconductors. We have reported an alternative AC dark-injection method giving access to in-plane transport parameters of organic semiconductor thin films. Exposing a metal-insulator-semiconductor structure to a periodic bias leads to a periodic change in surface potential which can be tracked via a Kelvin-Probe giving direct insight into the movement of lateral charge-carrier waves along the organic film. Based on a simple model the charge-carrier mobility of the semiconducting layer can be extracted from experimental data. In this study we further investigate the validity of the proposed model via two dimensional finite-element simulations. We investigate the influence of properties like doping concentration, traps states and applied bias on the device response. It is found that the model predicts the surface potential oscillations very well for a wide range of parameters. Ad-hoc expansions of the model to include additional effects such as doping and traps states further increase its accuracy, giving it a broad applicability if accurate experimental measurements of the mobility are needed.