Two-Dimensional Janus Antimony Selenium Telluride with Large Rashba Spin Splitting and High Electron Mobility

Janus two-dimensional materials with large Rashba spin splitting and high electron mobility are rarely reported but highly desired for nanoscale spintronics. Herein, using density functional theory calculations, we predicated Janus Sb₂Se_xTe_3–x (x = 1 or 2) monolayers simultaneously harboring these fascinating properties. The predicated monolayers are indirect semiconductors with great dynamical, thermal, and mechanical stability. The spin–orbital coupling (SOC) and the out-of-plane asymmetry lead to Rashba spin splitting at the conduction band minimum (CBM), which can be effectively tuned by the small uniaxial strain. The strong band dispersion at the CBM leads to small electron effective mass, consequently enabling a high electron mobility that reaches up to 6816.63 cm² V^–1 s^–1. Moreover, Janus Sb₂Se_xTe_3–x monolayers possess great light absorption capability within the visible and infrared regions of solar light. Our findings highlight promising candidates for high-speed spintronic devices and may motivate more research efforts on carrier transport and SOC effects in Janus group V and VI monolayers.