Imaging Fermi-level hysteresis in nanoscale bubbles of few-layer MoS2

The electrical stability and reliability of two-dimensional (2D) crystal-based devices are mainly determined by charge traps in the device defects. Although nanobubble structures as defect sources in 2D materials strongly affect the device performance, the local charge-trapping behaviors in nanobubbles are poorly understood. Here, we report a Fermi-level hysteresis imaging strategy using Kelvin probe force microscopy to study the origins of charge trapping in nanobubbles of MoS 2 on SiO 2 . We observe that the Fermi-level hysteresis is larger in nanobubbles than in flat regions and increases with the height in a nanobubble, in agreement with our oxide trap band model. We also perform the local transfer curve measurements on the nanobubble structures of MoS 2 on SiO 2 , which exhibit enhanced current-hysteresis windows and reliable programming/erasing operations. Our results provide fundamental knowledge on the local charge-trapping mechanism in nanobubbles, and the capability to directly image hysteresis can be powerful tool for the development of 2D material-based memory devices. Nanobubbles are sources of charge trapping that influence the performance and stability of devices based on 2D materials. Here, Kelvin probe force microscopy is used to study the origin and mechanism of charge trapping in nanobubbles of MoS 2 on a SiO 2 substrate.