Low-voltage organic thin-film transistors with large transconductance

We have developed an organic thin-film transistor (TFT) technology that aims at providing a good balance of static and dynamic performance parameters. An inverted staggered (bottom-gate, top-contact) device structure with patterned metal gates, a room-temperature-deposited gate dielectric providing a capacitance of 0.7μF∕cm2, and vacuum-deposited pentacene as the semiconductor were employed. The TFTs have a channel length of 10μm, a carrier mobility of 0.4cm2∕Vs, an on/off current ratio of 107, a subthreshold swing of 100mV/decade, and a transconductance per channel width of 40μS∕mm. Ring oscillators operate with supply voltages as low as 2V and with signal propagation delays as low as 200μs per stage.