Semiconducting versus Metallic Behaviors in Bilayer Buckled Phosphorene and Arsenene: The Role of Interlayer Orbital Hybridization

Abstract Two-dimensional (2D) bilayer materials are of particular interest as the interlayer interaction provides an additional degree of freedom to tune the electronic properties. Here, using density functional theory with Wannier analyses, we systematically investigate the stacking-dependent electronic phases in bilayer buckled phosphorene (blueP) and arsenene (β-As). We reveal that interlayer orbital hybridizations, such as s–s and pz–pz interactions, play a crucial role in determining the electronic structures. For bilayer blueP, the small interlayer distance leads to strong interlayer orbital hybridization, driving the system into a metallic state; for bilayer As, however, the larger equilibrium interlayer spacing results in much weaker interlayer interaction and thus a semiconducting phase. Furthermore, we uncover an anomalous band gap evolution in bilayer β-As under vertical pressure and show that in-plane strain can modulate the electronic phase transition. These findings highlight its potential for nanodevice applications, particularly pressure sensors, as supported by quantum transport calculations. Our findings not only elucidate the fundamental mechanism governing electronic behaviors in 2D bilayer structures, but also shed light on their significant potential for next-generation electronic and sensing devices.