Strain tunable structural, mechanical and electronic properties of monolayer tin dioxides and dichalcogenides SnX2 (X[dbnd]O, S, Se, Te).

The gap-strain curves of 2H-SnS 2 , 1T-SnS 2 and 1T-SnSe 2 are similarly parabolas, while SnO 2 decreases linearly with increasing strain. Notably, the slope of the band gap variation of the biaxial strained 1T-SnO 2 reaches up to −0.16 eV/1%. • The stiffness of 2H-SnX 2 is much higher. • The band gap of SnO 2 decreases linearly with increasing strain. • The gap-strain curves of 2H-SnS 2 , 1T-SnS 2 and 1T-SnSe 2 are similarly parabolas. • Small (1%) deformations can results in semiconductor-metal transitions. Based on first-principles calculations, we investigate the structural, mechanical and electronic properties of monolayer tin dioxides and dichalcogenides SnX 2 (X O, S, Se, Te) under uniaxial and biaxial strains. Our results show that monolayer 1T-SnX 2 is energetically more stable than 2H-SnX 2 , while the stiffness of 2H-SnX 2 is much higher. The unstrained SnX 2 is thermodynamically and dynamically more stable than the strained ones. We also show that when external strain is applied, the band gaps of both 2H- and 1T-SnO 2 decrease linearly with increasing strain, which is contributed by the strain induced orbital redistribution of the decomposition of the p orbital of X atom and s, p orbitals of Sn atom. Notably, the slope of the band gap variation of the biaxial strained 1T-SnO 2 reaches up to -0.16 eV/1%. In our calculations, strain can result in a semiconductor–metal transition of 2H-SnX 2 , while it only affects the band gap of 1T-SnX 2. [ABSTRACT FROM AUTHOR]