▎ 摘　　要

NOVELTY - A top floated gate Van der Waals heterojunction device comprises a hexagonal boron nitride nanosheet and a graphene nanosheet sequentially stacked on a molybdenum disulfide bottom electrode device, where the stacked molybdenum disulfide bottom electrode device, the hexagonal boron nitride nanosheet and the graphene nanosheet have a completely overlapping region in the vertical direction. USE - Top floated gate Van der Waals heterojunction device. ADVANTAGE - The top floated gate Van der Waals heterojunction device has better effect of enhancing the performance of the device, and multi-bit photoelectric large memory window, high on/off ratio, low dark current, rapid optical response, better stability and multi-bit storage performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) a method for preparing top floated gate Van der Waals heterojunction device (2) a nonvolatile memory device.