Toward negligible charge loss in charge injection memories based on vertically integrated 2D heterostructures

Two-dimensional (2D) crystals have a multitude of forms,including semi-metals,semiconductors,and insulators,which are ideal for assembling isolated 2D atomic materials to create van der Waals (vdW) heterostructures.Recently,artificially-stacked materials have been considered promising candidates for nanoelectronic and optoelectronic applications.In this study,we report the vertical integration of layered structures for the fabrication of prototype non-volatile memory devices.A semiconducting-tungsten-disulfide-channel-based memory device is created by sandwiching high-density-of-states multi-layered graphene as a carrier-confining layer between tunnel barriers of hexagonal boron nitride (hBN) and silicon dioxide.The results reveal that a memory window of up to 20 V is opened,leading to a high current ratio (＞103) between programming and erasing states.The proposed design combination produced layered materials that allow devices to attain perfect retention at 13％ charge loss after 10 years,offering new possibilities for the integration of transparent,flexible electronic systems.