【Device Papers】Gate-Reconfigurable ZnO/β-Ga₂O₃ Heterojunction Phototransistor Enabling Dual-Wavelength Ultraviolet Photoresponse and Optoelectronic-Synaptic Behaviors

      Researchers from Shenzhen University have published a dissertation titled " Gate-Reconfigurable ZnO/β-Ga₂O₃ Heterojunction Phototransistor Enabling Dual-Wavelength Ultraviolet Photoresponse and Optoelectronic-Synaptic Behaviors " in ACS Applied Electronic Materials.

Abstract

      A central challenge for next-generation intelligent optoelectronic systems is to co-integrate photodetection and neuromorphic in-sensor computing within a single device to eliminate redundant data transfer between physically separated units. Herein, we demonstrate a gate-reconfigurable ZnO/β-Ga₂O₃ heterojunction phototransistor that reconciles these two antagonistic functions via a bias-switchable carrier-transport pathway. The device design couples (i) a large interfacial conduction-band energetic step and (ii) oxygen-vacancy-related trap states distributed in the Ga₂O₃ layer, enabling the external gate voltage to toggle the dominant mechanism between rapid electron transfer/collection and O_v-mediated persistent photoconductivity (PPC). In the photodetection mode (V_G =+10V) under 366 nm illumination, the phototransistor exhibits a responsivity of 7.5 × 10⁴ A/W, a shot-noise-limited specific detectivity of 7.8 × 10¹⁴ Jones, and an external quantum efficiency of 3.8 × 10⁷%, with a weak optical intensity of 10 μW/cm². Complementary measurements at 290 nm further confirm the dual-wavelength ultraviolet response of the device. This mode enables optical ASCII communication and intensity-reconfigurable Boolean logic (AND/OR) within a single transistor. In the neuromorphic synapse mode (V_G = –10 V), enhanced electron confinement in the oxygen-vacancy-rich Ga₂O₃ layer activates pronounced PPC, enabling robust emulation of synaptic plasticity including paired-pulse facilitation (PPF), short-term-to-long-term (STP-LTP) plasticity transition, learning-forgetting-relearning, and Pavlovian conditioning under both 290 and 366 nm excitation. Moreover, leveraging PPC as a bio-inspired resource, we extend functionality to artificial nociceptors (hyperalgesia and allodynia) and dual-wavelength spatiotemporal encoding, highlighting a versatile materials/device strategy for integrated neuromorphic vision and programmable optoelectronic computing hardware.

DOI：

https://doi.org/10.1021/acsaelm.6c01368