75 kbit printed indium oxide (IO)/indium gallium zinc oxide (IGZO) heterojunction photoelectric synaptic transistor arrays for an artificial visual memory system

Abstract

With the advancement of neuromorphic electronics, the design and fabrication of large-scale and cost-effective photoelectric synaptic transistors have received much attention. Herein, we report for the first time the largest (75 kbit, i.e., 320 × 240) printed indium oxide (IO)/indium gallium zinc oxide (IGZO) heterojunction photoelectric synaptic transistor arrays with excellent photoelectric properties. The as-prepared IO/IGZO synaptic transistor devices exhibit outstanding electrical properties (high device uniformity, a high on/off ratio of ∼8.25 × 10⁷, a high mobility of ∼25.8 cm² V⁻¹ s⁻¹ and negligible hysteresis) and successfully demonstrate typical neuromorphic properties (short-term and long-term plasticity (STP/LTP) and paired-pulse facilitation (PPF)). In particular, such printed heterojunction synaptic transistors show ultralow power consumption (1.056 fJ per synaptic event) and tunable superior memory time (from 4.39 s to 400 s) to realize multi-state storage characteristics. Furthermore, 75 kbit printed IO/IGZO heterostructure photoelectric synaptic transistor arrays have been used to imitate traditional Pavlovian conditioning and artificial visual memory systems, which exhibit excellent durable visual detection and memory behaviors. The high device uniformity and outstanding electrical and neuromorphic properties are attributed to the high-quality IO/IGZO oxide heterostructure. This work establishes a dependable and efficient strategy for fabricating high-performance, large-area artificial visual synapses based on IO/IGZO heterojunction transistors for artificial visual memory chips.