Current-gain cutoff frequencies above 10 MHz for organic thin-film transistors with high mobility and low parasitic capacitance

The current-gain cutoff frequency for bottom contact n-channel C-60 thin-film transistors (TFTs) with channel lengths of 2-10 mu m has been investigated. Patterned gate electrodes were adopted to reduce parasitic capacitance of the TFTs. The cutoff frequency was estimated by direct measurement of the gate and drain modulation currents. The estimated cutoff frequency increases consistently with reducing channel length. A maximum cutoff frequency of 20.0 MHz was obtained from a C-60 TFT with a channel length of 2 mu m and a saturation mobility of 1.11 cm(2)/V s.