Characterization of ohmic contacts in polymer organic field-effect transistors

摘要: Abstract It is well known that contact resistance R c limits the performance of organic field-effect transistors (OFETs) have high mobilities (μ FET ≳ 0.3 cm 2  V −1  s ) and short channel lengths ( L ch  ≲ 30 μm). The usual transfer-line method (TLM) to analyze calls for extrapolation total zero at constant drain gate voltages. This requires an unrealistic assumption does not vary with source−drain current I sd (nor carrier density σ). Here we describe a self-consistent TLM analysis instead imposes condition σ. results explicitly reveal dependence on We further how this , σ) surface can be modelled yield specific resistivity ρ metal/organic semiconductor (OSC) interface, key parameter has so far been neglected in OFETs. illustrate application these analyses high-performance staggered top-gate bottom-contact poly(2,5-bis(alkyl)-1,4-dioxopyrrolo [3,4-c]pyrrole-3,6-diyl-terthiophene-2,5″-diyl) (DPPT2-T) OFETs fabricated bottom Au source–drain electrode arrays, contact-corrected μ 0.5 cm . show when electrodes are modified impose weak, then strong hole-doping DPPT2-T diminishes its dispersion, i.e. σ, weakens. ultimate attained strongly hole-doped ca 1 Ω cm broadly independent which propose hallmark true metal/OSC ohmic contact. For comparison, bare Au/DPPT2-T gives order 10 Ω cm marked σ dependence. lowest reached here shortens transfer length down 5 μm, enabling advantageously employed technology.