High-Frequency Organic Complementary Ring Oscillator Operating up to 200 kHz

Organic complementary circuits consisting of bottom-contact p-channel pentacene and n-channel C(60) thin-film transistors (TFTs) have been fabricated to evaluate their dynamic properties. Modified drain and source electrodes were used to balance the threshold voltages of the pentacene and C(60) TFTs. The balanced threshold voltage allowed use of equal-size channel dimensions for both channel-type TFTs in the circuits. The signal delay per stage of a five-stage ring oscillator was consistent with the mobilities of the individual TFTs. The oscillation frequency increased with supply voltage up to 200 kHz, which is the highest frequency in organic five-stage complementary ring oscillators. (C) 2011 The Japan Society of Applied Physics