Electrical Characterization of Pentacene-Based Organic Thin-Film Transistors

Organic thin-film transistors were formed on a pentacene active layer by using a back gate structure. Transistors were fabricated either on a, patterned pentacene film or on a. blank pentacene film to understand device performance in terms of pentacene film coverage. We found that the surface free energy of SiO(2) was closely related to the grain features in the pentacene film, affecting the leakage current level. The current flow path was identified by comparing topologies with current images. In the pentacene film, the current flows through grains rather than along the pentacene grain boundaries. The patterned pentacene thin-film transistor formed on dry oxidized SiO(2) showed better electrical properties in terms of mobility, on/off ratios and subthreshold swing.