Low voltage organic devices and circuits with aluminum oxide thin film dielectric layer

Low voltage operating organic devices and circuits have been realized using atomic layer deposition deposited aluminum ox- ide thin film as dielectric layer. The dielectric film has per unit area capacitance of 165 nF/cm2 and leakage current of 1 nA/cm2 at 1 MV/cm. The devices and circuits use the small-molecule hydrocarbon pentacene as the active semiconductor material. Transistors, inverters, and ring oscillators with operating voltage lower than 5 V were obtained. The mobility of organic field-effect transistors was extracted to be 0.16 cm2/Vs in saturation range, the threshold voltage is 0.3 V, and the on/off current ratio is larger than 105. The gain of inverters is estimated to be 12 at -5 V supply voltage, and the propagation delay is 0.25 ms per stage in 5-stage ring oscillators.