High performance of pentacene organic thin film transistors by doping of iodine on source/drain regions

Contact doping was conducted by iodine in a top contact configuration in a pentacene organic thin film transistor (OTFT), to investigate its effects on contact resistance and the resulting electrical performance. Iodine doping in the pentacene film caused the change of pentacene structure, thus leading to an increase in electrical anisotropy, i.e. ratio of lateral to vertical resistivity. The two resistive components of doped pentacene film underneath the Au contacts were major contributors to the contact resistance, and a model to explain the dependence of contact resistance on iodine doping was presented. Finally, OTFTs fabricated on iodine doped source/drain contacts exhibited high mobility of 1.078 cm2/V s, two times that of OTFTs with undoped contacts, due to the low contact resistance.

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► We have investigated the effect of iodine doping on structural evolution of pentacene thin film.
► The resulting electrical anisotropy (lateral and vertical resistivities) of pentacene thin film was also investigated.
► Pentacene OTFTs with doped contacts were fabricated to measure the electrical characteristics.
► A model was presented to show the effect of iodine doping on S/D contact resistance.