Tuning transport coefficients of monolayer MoSi₂N₄ with biaxial strain*

Abstract

Experimentally synthesized MoSi2N4 (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 MoSi2N4 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 MoSi2N4 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 MoSi2N4, 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 MoSi2N4, and can motivate farther experimental exploration.

Substitutional transition metal doping in MoSi2N4 monolayer: structural, electronic and magnetic properties

“…1(c and d) show the band structure, density of states (DOS), and partial DOS (PDOS) of MoSiN nanosheet, indicating that it is a semiconductor with an indirect bandgap (E g ) of 1.74 eV with the valence band maximum (VBM) and conduction band minimum (CBM) located at the G and K points, respectively. The calculated band structure and DOS/PDOS spectra and bandgaps agree well with the previous theoretical reports 31,37,38 and with the experimental bandgap (1.94 eV). 27 The bandgap calculated with the hybrid functional (HSE06) is 2.35 eV, 27 higher than the experimental value.…”

“…29 This made MoSiN the focus of intensive research aiming to uncover its novel properties. [30][31][32][33][34][35][36][37][38][39] Following the successful MoSiN preparation, many MX 2 Y 4 (M = Cr, V, Mo, W, Ta; X = Si, Ge; and Y = N, As, P) monolayers have been studied. 40,41 It was found that WSi 2 N 4 , CrSi 2 N 4 , and MoSi 2 N 4 monolayers have the highest piezoelectric coefficients as compared with the other known 2D materials.…”

Strain effects on monolayer MoSi2N4: Ideal strength and failure mechanism

“…The moderate band gap, high mobility, and excellent stability of monolayer MoSi 2 N 4 promise its advantages in nano-electronic and optoelectronics. Since the experimental synthesis of layered MoSi 2 N 4 , an enormous amount of research efforts have been devoted to exploring its various properties [17][18][19][20][21][22][23][24][25][26][27]. Density functional theory (DFT) calculations indicated that monolayer MoSi 2 N 4 has a larger Poisson's ratio (0.28) [17] than that of graphene (0.16) [28].…”

Analysis of Tencent’s Successful Development Strategy

“…According to figure 2, it is obvious from the chart that the mobile phone market in China each year had an extremely big enhancement which reached peak in 2016, despite a small amount decrease in 2017. [6]But overall, the surge of the whole mobile phone market is in this also means that consumers can more easily buy a reasonable price and accept the mobile phone . With the support of the mobile phone market, Tencent gradually launched Wechat, the software, and added more novel functions such as: WeChat Pay, Mini Programs, and Game Center are very popular among consumers.…”