Large out-of-plane piezoelectric response and ultra-low polarization transition barriers in two-dimensional MoGe2N4/MoSi2N4 heterostructures

Abstract

With the help of the first principle calculations, two-dimensional (2D) MoGe2N4/MoSi2N4 van der Waals (vdW) heterojunction was confirmed as a type II bandgap arrangement with distinct piezoelectric properties dependent on the stacking orders and interlayer interactions. This structural change is facilitated by slip interactions between the layers and is characterized by a process with a low energy barrier, allowing for efficient and responsive phase transition of structures. Notably, this heterojunction exhibits a particularly large out-of-plane piezoelectric coefficient, d33, within a finite thickness. Concurrently, the piezoelectric coefficient can be enhanced by adjusting the vertical strain to a specific value, and the out-of-plane piezoelectric coefficient d33 can be as high as 73.28 pm/V, which is larger than the values of the available 2D materials or their heterojunctions. In addition, we simulated a piezoelectric actuator on a two-dimensional scale, where the deformation of the upper surface of the piezoelectric brake was linearly modulated by adjusting the driving voltage, Thus, our research paves the way for the conceptualization and creation of cutting-edge nanoelectronic devices, electromechanical systems, and multifunctional atomic-scale appliances.