Multi-Bit Floating-Gate Memory with an Ultrawide Programmable Window

The rapid growth of data-intensive computing and optoelectronic information processing demands memory devices with high density, multilevel programmability, and fast operation. Floating-gate memory has attracted considerable attention due to its reliable charge-storage characteristics, but it is still limited by low storage density, restricted multilevel capability, and the lack of optoelectronic integration. Here, we report a Molybdenum ditelluride/hexagonal boron nitride/multilayer graphene (MoTe₂/hBN/MLG) van der Waals heterojunction that achieves an ultrawide p-type memory window (∼199.2 V), a high memory window ratio of 90.5%, and an ultrahigh storage density (>10¹³ cm^-2). Our device demonstrates an ultrafast response speed of 50 ns, robust endurance over 10⁶ cycles, and reliable data retention projected for 10 years. Under electrical pulse modulation, we achieved multilevel memory exceeding 6 bits and successfully emulated synaptic plasticity. Furthermore, robust negative photoconductance (NPC) enables laser-driven optical modulation with multilevel memory exceeding 7 bits. In addition, we employed a hybrid digital-analog architecture to simulate in-memory computing for CIFAR-10 image classification, achieving an accuracy exceeding 95%, comparable to pure digital implementations. Together, these advances position our device as a promising building block for scalable neuromorphic and optoelectronic information technologies.