Experimentally synthesized MoSi_(2)N_(4)(Science 369 670(2020)) is a piezoelectric semiconductor. Here, we systematically study the large biaxial(isotropic) strain effects(0.90–1.10) on electronic structures and tran...Experimentally synthesized MoSi_(2)N_(4)(Science 369 670(2020)) is a piezoelectric semiconductor. Here, we systematically study the large biaxial(isotropic) strain effects(0.90–1.10) on electronic structures and transport coefficients of monolayer MoSi_(2)N_(4) by density functional theory(DFT). With a/a0 from 0.90 to 1.10, the energy band gap firstly increases, and then decreases, which is due to transformation of conduction band minimum(CBM). Calculated results show that the MoSi_(2)N_(4) monolayer is mechanically stable in the considered strain range. It is found that the spin-orbital coupling(SOC) effects on Seebeck coefficient depend on the strain. In unstrained MoSi_(2)N_(4), the SOC has neglected influence on Seebeck coefficient. However, the SOC can produce important influence on Seebeck coefficient, when the strain is applied,for example, 0.96 strain. The compressive strain can change relative position and numbers of conduction band extrema(CBE), and then the strength of conduction bands convergence can be enhanced, to the benefit of n-type ZT_e. Only about0.96 strain can effectively improve n-type ZT_e. Our works imply that strain can effectively tune the electronic structures and transport coefficients of monolayer MoSi_(2)N_(4), and can motivate farther experimental exploration.展开更多
基金supported by the Natural Science Basis Research Plan in Shaanxi Province of China (Grant No. 2021JM-456)。
文摘Experimentally synthesized MoSi_(2)N_(4)(Science 369 670(2020)) is a piezoelectric semiconductor. Here, we systematically study the large biaxial(isotropic) strain effects(0.90–1.10) on electronic structures and transport coefficients of monolayer MoSi_(2)N_(4) by density functional theory(DFT). With a/a0 from 0.90 to 1.10, the energy band gap firstly increases, and then decreases, which is due to transformation of conduction band minimum(CBM). Calculated results show that the MoSi_(2)N_(4) monolayer is mechanically stable in the considered strain range. It is found that the spin-orbital coupling(SOC) effects on Seebeck coefficient depend on the strain. In unstrained MoSi_(2)N_(4), the SOC has neglected influence on Seebeck coefficient. However, the SOC can produce important influence on Seebeck coefficient, when the strain is applied,for example, 0.96 strain. The compressive strain can change relative position and numbers of conduction band extrema(CBE), and then the strength of conduction bands convergence can be enhanced, to the benefit of n-type ZT_e. Only about0.96 strain can effectively improve n-type ZT_e. Our works imply that strain can effectively tune the electronic structures and transport coefficients of monolayer MoSi_(2)N_(4), and can motivate farther experimental exploration.
