论文标题
调整单层$ \ mathrm {mosi_2n_4} $带有双轴应变的传输系数
Tuning transport coefficients of monolayer $\mathrm{MoSi_2N_4}$ with biaxial strain
论文作者
论文摘要
实验合成的$ \ MATHRM {MOSI_2N_4} $（\ TextColor [RGB] {0.00,0.00,00,1.00} {Science 369，670-674（2020）}）是一个压电性半导体。在这里，我们系统地研究了通过密度功能理论（DFT）的单层$ \ mathrm {mosi_2n_4} $的电子结构和传输系数的大型双轴（各向同性）应变效应（0.90至1.10）。 $ A/A_0 $从0.90到1.10，能量频段隙首先增加，然后减小，这是由于传导带最小值（CBM）的转换所致。计算结果表明，$ \ mathrm {mosi_2n_4} $单层在被考虑的应变范围内机械稳定。发现自旋轨道耦合（SOC）对Seebeck系数的影响取决于菌株。在未经培训的$ \ mathrm {mosi_2n_4} $中，SOC忽略了对Seebeck系数的影响。但是，当应用应变时，SOC可以对Seebeck系数产生重要影响，例如0.96菌株。压缩应变可以改变相对位置和传统带极值（CBE）的数量，然后可以增强导带的强度，从而增强n型$ ZT_E $的好处。只有大约0.96的应变可以有效地改善n型$ zt_e $。我们的作品暗示应变可以有效调整单层$ \ mathrm {mosi_2n_4} $的电子结构和传输系数，并可以激励更远的实验探索。
Experimentally synthesized $\mathrm{MoSi_2N_4}$ (\textcolor[rgb]{0.00,0.00,1.00}{Science 369, 670-674 (2020)}) is a piezoelectric semiconductor. Here, we systematically study the large biaxial (isotropic) strain effects (0.90 to 1.10) on electronic structures and transport coefficients of monolayer $\mathrm{MoSi_2N_4}$ by density functional theory (DFT). With $a/a_0$ 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 $\mathrm{MoSi_2N_4}$ monolayer is mechanically stable in considered strain range. It is found that the spin-orbital coupling (SOC) effects on Seebeck coefficient depend on the strain. In unstrained $\mathrm{MoSi_2N_4}$, 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 about 0.96 strain can effectively improve n-type $ZT_e$. Our works imply that strain can effectively tune the electronic structures and transport coefficients of monolayer $\mathrm{MoSi_2N_4}$, and can motivate farther experimental exploration.
