Novel Two-Dimensional Semiconductor SnP3 with High Carrier Mobility, Good Light Absorption, and Strong Interlayer Quantum Confinement

We propose a novel two-dimensional (2D) SnP3 crystal that possesses low indirect band gaps of 0.67 eV (monolayer) and 1.03 eV (bilayer) and high kinetic and thermal stability until 500 K. The 2D SnP3 shows strong interlayer quantum confinement effects, resulting in a band gap increase from mono- to bilayer, and then a band gap decrease from bi- to triple layer leading to a semiconductor–metal transition. Monolayer SnP3 has large hole mobility (992 cm2 V–1 s–1), whereas bilayer SnP3 has high electron mobility (8002 cm2 V–1 s–1) which is comparable to that of phosphorene. The static dielectric constants of mono- and bilayer SnP3 are 3.21 and 5.24, respectively. Both monolayer and bilayer SnP3 show strong light absorption in the visible and ultraviolet regions. The indirect band gap of monolayer SnP3 decreases under biaxial compressive strain and increases under biaxial tensile strain. Especially, when the biaxial compressive strain reaches to 6%, monolayer SnP3 has a transition from semiconductor to metal. These results indicate that mono- and bilayer SnP3 are promising novel 2D materials that have great potential applications in electronic and optoelectronic devices.