Semiconductor Functional Device Group

We have been developing new types of logic circuits to overcome the limits of modern von Neumann type device architecture. A key element is an antiambipolar transistor (AAT), where a p-n heterojunction plays critical role in controlling electrical currents. The uniqueness of AATs can be ascribed to their distinctive electrical properties; negative differential transconductance can be manipulated, peak-to-valley ratios of which are ranging in 10⁰-10⁵. By taking this advantage, we have developed multi-valued logic circuits, reconfigurable logic gates, optically controllable logic-in-memory and artificial synaptic devices. These logic operations have been developed with organic semiconductors and two-dimensional atomic layers.

In 2025, We developed a new type of neuromorphic device, in which both potentiation and depression properties were induced by consistent input pulses (V_SG). This was realized in an antiambipolar transistor with an organic heterojunction and a HfO₂/Au/HfO₂ multilayer as a memory layer.