Efficient UV-Sensitive Si-In-ZnO-Based Photo-TFT and Its Behavior as an Optically Stimulated Artificial Synapse

Abstract

Integration of optoelectronic synaptic devices as neuromorphic vision sensors has currently attracted significant attention due to their ability of imitating human visual systems. Low-power-consuming UV-sensitive phototransistors fabricated using amorphous oxide semiconductors are one of the potential contenders for the development of optically stimulated synaptic devices. Herein, amorphous Si-In-ZnO (a-SIZO)-based UV-sensitive photo thin-film transistors (photo-TFTs) were fabricated, which exhibited an efficient spectral photoresponsivity of 4.93 × 103 A/W and detectivity of 5.47 × 1015 jones at 350 nm wavelength. Considerable photoresponse in the visible range (450–650 nm) was also observed. The presence of persistent photoconductivity (PPC) in the photoresponse characteristics enabled the photo-TFT to perform simultaneously as an optically stimulated artificial synapse. The typical synaptic behaviors such as excitatory post-synaptic current (EPSC), pair-pulse facilitation (PPF), short-term plasticity (STP) to long-term plasticity (LTP), etc. were demonstrated efficiently by the fabricated photo-TFT, indicating its learning and memorizing capabilities similar to a biological synapse. The concurrent demonstration of efficient UV range photoresponse and optically stimulated synaptic behavior enables the a-SIZO-based photo-TFT as a promising pathway toward the development of artificial visual sensors which can be integrated into future neuromorphic systems.