Photonic Modulation of Negative Differential Transconductance for Tunable Multivalued Logic in Heterojunction Transistors.

Logic conversion within multivalued logic (MVL) circuits is a promising solution that enhances complex data processing achieved through the modulation of negative differential transconductance (NDT) characteristics of heterojunction transistors (HTRs) using various external control factors. Among these factors, utilizing photonic modulation for logic switching facilitates multi-state operations, enables wavelength-selective logic conversion and, on this basis, enhances the flexibility of the circuit system. Herein, the implementation of logic conversion in HTRs through the photonic modulation of NDT characteristics is presented. Logic switching in the InO/PDPP3T HTR is enabled by tuning its NDT characteristics utilizing optical stimulation with LED light at a specific wavelength. Moreover, operating the HTR through photonic control reduces process requirements while ensuring stable operation, thereby enhancing compatibility and scalability in circuit design. The operating mechanism of the device is also investigated by individually analyzing the carrier flows in two paths and examining the electrical characteristics under dark and illuminated states. To verify the functionality of the MVL circuit, stable switching between binary and ternary logic inverters as a practical application is demonstrated.