Highly anisotropic electronic and mechanical properties of monolayer and bilayer As<inf>2</inf>S<inf>3</inf>

Two-dimensional(2D) material with high anisotropy as well as robust stability would inspire significant interest in the new-generation electronic and optomechanical field, especially for directional memories, synaptic, neuromorphic and polarization-sensitive photodetector devices. Recently, 2D As2S3 was successfully exfoliated in experiments (Šiškins et al., 2019) and was demonstrated to be stable in the ambient. Herein, by using first principles method, we further systematically predicted its angular-dependent electronic and mechanical properties. Specifically, the angle-resolved effective mass of carriers, carrier mobility, three dimensional band structure, stress–strain relationships, as well as the angle-dependent mechanical properties are investigated. Our results show that 2D As2S3 owns a high anisotropic nature both electronically and mechanically. We found that, due to the large anisotropic charge distributions, 2D single (bilayer) As2S3 has shown a value of 3.15 (3.32) in Young's modulus ratio along two axes. These values are much greater than the corresponding 2D black phosphorous of 2 (Tao et al., 2015), which is experimentally confirmed the largest one up to date. Our findings provide an valuable avenue to realize the flexible orientation-dependent nano-devices