Short-Channel Vertical Organic Field-Effect Transistors with High On/Off Ratios

A unique vertical organic field-effect transistor structure in which highly doped silicon nanopillars are utilized as a gate electrode is demonstrated. An additional dielectric layer, partly covering the source, suppresses bulk conduction and lowers the OFF current. Using a semiconducting polymer as active channel material, short-channel (100 nm) transistors with ON/OFF current ratios up to 10(6) are realized. The electronic behavior is explained using space-charge and contact-limited current models and numerical simulations. The current density and switching speed of the devices are in the order of 0.1 A cm(-2) and 0.1 MHz, respectively, at biases of only a few volts. These characteristics make the devices very promising for applications where large current densities, high switching speeds, and high ON/OFF ratios are required.