Chevron-type gate configuration of short channel top-contact organic thin-film transistors for large saturated drain current

We demonstrate a chevron-type gate configuration of a short channel top-contact organic thin-film transistor (OTFT) showing large saturated drain current with the help of a polymeric edge support. The channel length (L) depends on the geometrical shape of the edge support which can be controlled by thermal treatment. Oblique deposition of Au onto the substrate with the edge support allows a self-defined channel length down to a submicrometre scale. The chevron-type top-contact OTFT with L = 0.8 μm exhibits a drain current per channel width as large as 80 μA mm^-1 at the operating voltage of -3 V. The leakage current associated with a gate insulator AlO_x is systematically investigated in a metal-insulator-metal structure and a metal-insulator-semiconductor-metal structure by varying the O₂ plasma treatment and the pentacene thickness. Using the optimized gate insulator AlO_x, a saturation behaviour of the output characteristic curve, low current leakage and low voltage operation are achieved in our chevron-type OTFT.