topological insulators and semimetals, have been proposed as potential candidates in the post-silicon era. [1-13] From a technological point of view, 2D materials, especially their single-crystalline forms, are superior if considering their intrinsic thinness and potential availability at a large scale. [14-16] Besides, those 2D materials without dangling bonds at their surfaces are also stable and easy to be stacked into complexed multilayers, e.g., the so-called van der Waals (vdW) heterostructures, through artificial assembling of individual atomic layers in a chosen sequence. Such a stacking strategy is nearly free of those interface limitations, such as the lattice mismatch and inter diffusion, usually present in previous thin film deposition process. [11,17] The produced vdW heterostructures have been not only offered a great opportunity to address many novel physic problems but also used in various 2D materials based functional devices. [18-22] So far, 2D materials have grown up to a big family. Following the discovery of graphene, [5] hundreds of 2D materials such as hexagonal boron nitride (hBN), [23] transition-metal dichalcogenides, [9,13] 2D materials are promising building blocks for novel electronic devices. It is possible that future electronic devices will be entirely made of 2D materials to fully realize their potential, due to their natural thinness, atomically flat surface/interfaces and diverse properties. In this work, three typical 2D materials, i.e., monolayer molybdenum disulfide (MoS 2), hexagonal boron nitride (hBN), and few layer graphene (FLG) serving as semiconducting, dielectric, and contact/gating materials, respectively, are assembled for vertically integrated multilayer devices via the layer-by-layer stacking process. An individual layer of all-2D field effect transistors (FETs) shows comprehensive device performances with parameters of ultralow off-current ≈100 fA, ultrahigh on/ off ratio approaching to 10 10 , ideal subthreshold swing (SS) ≈100 mV dec −1 , and decent room temperature mobility up to 52 cm 2 V −1 s −1 , benefiting from the effective dual-gate modulation and high contact quality. Vertically stacked multilayers of all-2D FETs are successfully achieved with nearly multiplied oncurrent density, equivalent device mobility, and persevered on/off ratio and SS of the individual layers. The vertical integration of multilayered devices with different layer functions, e.g., memory, logic and sensor, are further demonstrated. This work provides a technological base for future high-performance integrated devices based on all-2D materials.
