Molecular dynamics modelling for nanoindentation effects of puckered arsenene

Abstract Molecular dynamics modelling was employed to investigate the nanoindentation effects of puckered arsenene. The influences of substrate size, temperature, loading rate, initial pressure, and layer number on the mechanical properties of arsenene including indentation force, stress, strain, and crack formation, were examined. The results indicate that as the substrate size increases, both the maximum load-bearing capacity and the indentation depth increase, and also an increased loading rate enhances peak load measurements. In monolayer arsenene, crack propagation initially proceeds along the armchair direction before transitioning to the zigzag direction. This anisotropic behaviour arises because stress along the zigzag direction significantly alters the in-plane bond angles, ultimately leading to structural failure. Furthermore, elevated temperatures facilitate the rupture of internal covalent bonds, resulting in a reduction of the substrate's Young's modulus and elastic limit, as well as a decrease in the initial crack propagation rate. In multilayer arsenene nanoindentation simulations, the crack propagation pattern in the bottommost layer aligns with that of monolayer arsenene, whereas initial pressure and layer count exhibit no significant correlation. This study determined the Young's modulus of monolayer arsenene to be 66.1 GPa, while bilayer to pentalayer configurations exhibited a range of 50~110 GPa, aligning with existed experimental reports (44.3 GPa armchair; 73.2 GPa zigzag). These findings provide crucial fundamental data for predicting the mechanical behaviour of arsenene in nanodevice applications, and the corresponding characterization methodology demonstrates potential for extension to other Group-V layered crystalline materials.