Top-Split-Gate Ambipolar Organic Thin-Film Transistors

Split-gate ambipolar organic transistor technology is gaining interests as a practical solution for the implementation of complementary transistors. It is known that conventional ambipolar transistors suffer from poor DC gain, noise margin, and high power consumption, as they do not have a well-defined off-state region. A split-gate device structure enables ambipolar transistors operating in a controlled unipolar mode (both p-type and n-type), resulting in superior inverter characteristics. A key challenge in previously reported split-gate ambipolar organic thin-film transistors is the strong current-voltage instabilities due to charge trapping at the dielectric interface. Here, the first split-gate ambipolar organic transistors with top-gate/bottom-contact structure are demonstrated. Compared to the previous split-gate devices, the top-split-gate ambipolar organic transistor exhibits superior electrical properties. The proposed device shows hysteresis-free I-V characteristics as well as higher bias stress stability. Furthermore, the complementary inverter circuit using the proposed transistors is also demonstrated, which results in a higher output swing and DC gain compared to the baseline ambipolar inverter.