Heterosynaptic Memtransistors Based on Switching Operation Mechanism Using Designed Organic/Inorganic Heterostructures for Neuromorphic Electronics

Memtransistors using low-dimensional semiconductors represent a promising gate-tunable heterosynaptic architecture for neuromorphic computing. However, active layers of these devices have not yet been artificially designed or controlled. In this study, gate-pulse-tunable heterosynaptic neuromodulation is achieved using memtransistors with organic semiconductor tris(4-carbazoyl-9-ylphenyl)amine (TCTA)/MoS₂ heterostructures designed via energy-band engineering and bottom-contact architecture. Memristive switching is realized through distinctive low- and high-conduction states with a switching ratio of 10², modulated by gate pulses. As the gate voltage (V_G) decreases from +30 to -30 V, the memristive hysteresis for the bottom contact TCTA/MoS₂ FET without post-treatment and an h-BN insulating layer appears at V_G = -15 V and broadens with an increasing switching ratio. Intriguingly, as V_G becomes increasingly negative (V_G < -15 V), trap-related space-charge-limited conduction becomes dominant. Non-volatile heterosynaptic behavior is mimicked by drain pulses and modulated by gate-pulse polarities. Applying gate-pulse only, analogous responses are observed in synaptic modulation with time constants of 100 ms for potentiation and 60 ms for depression. The design of multi-functional memory and realization of gate-pulse-tunable memtransistors using nanoscale TCTA/MoS₂ can promote energy-efficient, tunable, and reliable heterosynaptic neuromorphic electronics.