Investigation of Gate Direct-Current and Fluctuations in Organic p-Type Thin-Film Transistors

Investigation of gate dielectric conduction properties in organic p-type staggered thin-film transistors is reported by means of direct-current, capacitance-voltage, and noise measurements. Results suggest that transport in the CYTOP (TM) gate dielectric is dominated, at low currents, by Schottky conduction due to the emission at the aluminum gate interface through a barrier phi(B) approximate to 1 eV, while is limited, at higher currents, by space-charge conduction in the trap-limited regime with an effective mobility mu(theta) estimated in the order of 10(-9) cm(2)/(Vs). Gate current noise follows a 1/f law and it is found to be proportional to I-G(2), which is inconsistent with the commonly assumed mobility fluctuation. Traps responsible for gate noise are dielectric-bulk traps, not located at the semiconductor interface, since the gate noise is found to be uncorrelated with drain noise.