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 CYTOPTM gate dielectric is dominated, at low currents, by Schottky conduction due to the emission at the aluminum gate interface through a barrier φ
_B
≈ 1 eV, while is limited, at higher currents, by space-charge conduction in the trap-limited regime with an effective mobility μ
_θ
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
²
_G
, 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.