Theoretical Predition of Two-dimensional SiGeP₂ by the Global Optimization Method

Abstract

The well-developed particle-swarm optimization method together with density functional theory calculations were employed to search lowest-energy geometric structures of two-dimensional (2D) SiGeP₂. Two newly found structures (P3m1 and Pmm2) are predicted. The unbiased global search reveals that the two lowest-energy structures are honeycomb lattices with robust dynamical stabilities. A more accurate Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional is used to estimate the band structures of SiGeP₂, which indicates that both the structures are semiconductors with indirect band-gap energies 1.80 eV for P3m1 and 1.93 eV for Pmm2, respectively. Using the deformation potential theory, the P3m1-SiGeP₂ is predicted to have high electron mobilities (6.4×10⁴ along zigzag direction and 2.9×10³ cm²·V⁻¹·s⁻¹ along armchair direction, respectively) and hole electron mobilities (1.0×10³ along zigzag direction and 2.5×10³ cm²·V⁻¹·s⁻¹ along armchair direction, respectively), which can be comparable with that of phosphorene and show anisotropic character in-plane. In addition, to estimate the elastic limit of SiGeP₂, we also calculated the surface tension of SiGeP₂ as a function of tensile strain. Our results show that the 2D SiGeP₂ may be good candidaticates for applications in nanoelectronic devices.

Keywords

two dimensional SiGeP₂ / the first-principles / carrier mobility