High conductance bottom-contact pentacene thin-film transistors with gold-nickel adhesion layers

Bottom-contact pentacene thin-film transistors (TFTs) with different electrode types have been fabricated to investigate influence of the adhesion layers and surface modification on the transistor characteristics. Gold-nickel alloy or Ti was used for the adhesion layer; the drain/source electrodes were modified with pentafluorobenzenethiol (PFBT) or nonmodified. The TFTs with AuNi layers and PFBT-modified electrodes exhibit channel-length independent saturation mobility. The electrode-type TFT with a channel length of 2.2 μm has a saturation mobility of 0.73 cm2/V s and a transconductance of 229 μS/mm. The high performance is attributed to the low contact resistance of 408 Ω cm.