21 September 2005 Comparison between the charge carrier mobilities in pentacene OFET structures as obtained from electrical characterization and potentiometry
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Abstract
Potentiometry with a Kelvin probe atomic force microscope is used to investigate the contact resistances of pentacene OFETs, so that the injection of the charges at the source contact and their extraction at the drain contact can be distinguished from the influence of trap states on the charge transport through the accumulation channel. The samples consist of Au bottom contacts on a SiO2 gate dielectric with a channel length of L=10- 15 μm and a channel width of W=100 μm. The gate oxide is first treated by an oxygen plasma before depositing about 30 nm of pentacene under high vacuum conditions. The output characteristics are measured as a function of temperature in an evacuated cryostat, revealing temperature-activated hole transport. The potentiometry measurements are performed ex situ under atmospheric conditions after storing the samples in air for several weeks. At room temperature, the pentacene OFETs are dominated by the resistance at the injection contact, so that the mobility in the channel region as deduced from potentiometry is about one order of magnitude higher than the value obtained from the output characteristics. The measurements are interpreted with microscopic model calculations for the temperature-activated currents.
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R. Scholz, R. Scholz, A.-D. Müller, A.-D. Müller, F. Müller, F. Müller, I. Thurzo, I. Thurzo, B. A. Paez, B. A. Paez, L. Mancera, L. Mancera, D. R. T. Zahn, D. R. T. Zahn, C. Pannemann, C. Pannemann, U. Hilleringmann, U. Hilleringmann, } "Comparison between the charge carrier mobilities in pentacene OFET structures as obtained from electrical characterization and potentiometry", Proc. SPIE 5940, Organic Field-Effect Transistors IV, 59400I (21 September 2005); doi: 10.1117/12.617004; https://doi.org/10.1117/12.617004
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