Highly Reliable Van Der Waals Memory Boosted by a Single 2D Charge Trap Medium

Charge trap materials that can store carriers efficiently and controllably are desired for memory applications. 2D materials are promising for highly compacted and reliable memory mainly due to their ease of constructing atomically uniform interfaces, however, remain unexplored as being charge trap media. Here it is discovered that 2D semiconducting PbI₂ is an excellent charge trap material for nonvolatile memory and artificial synapses. It is simple to construct PbI₂-based charge trap devices since no complicated synthesis or additional defect manufacturing are required. As a demonstration, MoS₂/PbI₂ device exhibits a large memory window of 120 V, fast write speed of 5 µs, high on-off ratio around 10⁶, multilevel memory of over 8 distinct states, high reliability with endurance up to 10⁴ cycles and retention over 1.2 × 10⁴ s. It is envisioned that PbI₂ with ionic activity caused by the natively formed iodine vacancies is unique to combine with unlimited 2D materials for versatile van der Waals devices with high-integration and multifunctionality.