title: Mobility overestimation due to gated contacts in organic field-effect transistors.
abstract: Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current-voltage characteristics and interpreted by using the classical metal oxide-semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm(2) V(-1) s(-1)), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current-voltage characterization are overestimated by one order of magnitude or more.
authors.affiliation: National Institute of Standards and Technology, Engineering Physics Division, 100 Bureau Drive, MS 8120, Gaithersburg, Maryland 20899, USA.|Department of Physics, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA.
authors.forename: Emily G
authors.initials: EG
authors.lastname: Bittle
authors.affiliation: National Institute of Standards and Technology, Engineering Physics Division, 100 Bureau Drive, MS 8120, Gaithersburg, Maryland 20899, USA.|Department of Electrical Engineering, The Pennsylvania State University, 121 Electrical Engineering East, University Park, State College, Pennsylvania 16802, USA.
authors.forename: James I
authors.initials: JI
authors.lastname: Basham
authors.affiliation: Department of Electrical Engineering, The Pennsylvania State University, 121 Electrical Engineering East, University Park, State College, Pennsylvania 16802, USA.
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Jackson
authors.affiliation: Department of Physics, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, USA.
authors.forename: Oana D
authors.initials: OD
authors.lastname: Jurchescu
authors.affiliation: National Institute of Standards and Technology, Engineering Physics Division, 100 Bureau Drive, MS 8120, Gaithersburg, Maryland 20899, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Gundlach
mesh_terms: D058266:Dielectric Spectroscopy; D008422:Materials Testing; D009279:Naphthacenes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014173:Transistors, Electronic
chemical_list: D009279:Naphthacenes; C045049:rubrene; D012822:Silicon Dioxide