Ambipolar semiconducting materials, in which both holes and electrons can be modulated simultaneously, provide a simple approach toward complementary transistors and circuits. Manufacturing these ambipolar transistors on a substrate dramatically reduce the complexity of the fabrication process such as the separate deposition, patterning and optimization of two different semiconducting materials.

However, these transistors do not have a well-defined off-state region. As a result, the DC gain, noise margin, and power consumption in an inverter suffer from the fact that always one of the transistors in the inverter cannot be switched off completely, and this in turn results in the typical Z-shaped inverter characteristic.

The proposed split-gate ambipolar transistors operate as an either unipolar p-type and n-type device depending on the voltage bias at the secondary-gate. In the devices, carrier charges can only be injected from the source electrode (VS = 0 V) over the whole range of applied gate voltage. In this case, the secondary-gate is set to have same voltage as the drain electrode, screening the electric field from the main-gate to the drain electrode.

Complementary inverter using split-gate ambipolar transistors can be made. The secondary-gate electrode for p-type operation was connected to GND and the secondary-gate electrode for n-type operation was connected to VDD. Complementary inverters were demonstrated using the split-gate ambipolar transistors, which showed improved DC gain, output swing, and leakage current compared to conventional ambipolar inverters.