Charge carrier mobility is an important characteristic of organic field-effect transistors (OFETs) and other semiconductor devices. However, accurate mobility determination in FETs is frequently compromised by issues related to Schottky-barrier contact resistance, that can be efficiently addressed by measurements in 4-probe/Hall-bar contact geometry. Here, it is shown that this technique, widely used in materials science, can still lead to significant mobility overestimation due to longitudinal channel shunting caused by voltage probes in 4-probe structures. This effect is investigated numerically and experimentally in specially designed multiterminal OFETs based on optimized novel organic-semiconductor blends and bulk single crystals. Numerical simulations reveal that 4-probe FETs with long but narrow channels and wide voltage probes are especially prone to channel shunting, that can lead to mobilities overestimated by as much as 350%. In addition, the first Hall effect measurements in blended OFETs are reported and how Hall mobility can be affected by channel shunting is shown. As a solution to this problem, a numerical correction factor is introduced that can be used to obtain much more accurate experimental mobilities. This methodology is relevant to characterization of a variety of materials, including organic semiconductors, inorganic oxides, monolayer materials, as well as carbon nanotube and semiconductor nanocrystal arrays.
|Journal||Advanced Functional Materials|
|State||Published - Jun 27 2018|
Bibliographical noteFunding Information:
The authors are grateful to the following programs for the financial support of this work: the National Science Foundation under the grant DMR-1506609, the Rutgers Energy Institute (REI), the Center for Advanced Soft-Electronics funded by the Ministry of Science, ICT and Future Planning as Global Frontier Project (CASE-2011-0031628), and the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (№ K3-2016-004), implemented by a governmental decree dated 16th of March 2013, N 211. T.D.A., and A.F.P, acknowledge the King Abdullah University of Science and Technology (KAUST) for financial support.
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- conjugated polymers
- field-effect transistors
- molecular crystals
- organic semiconductors
ASJC Scopus subject areas
- Chemistry (all)
- Materials Science (all)
- Condensed Matter Physics