We have studied the disordered rocksalt, orthorhombic, and disordered wurtzite phases of the ternary nitride semiconductor MgSnN₂ by first-principles methods using density functional theory (DFT) and beyond. The results imply that MgSnN₂ is mechanically and dynamically stable in all three phases. However, pCOHP analysis suggests that the disordered rocksalt structure has antibonding states below the Fermi level between −5 eV and −2 eV, as compared to the bonding states in the other two phases, indicative of its thermodynamic metastability. Computed lattice constant and electronic band-gap values of 4.56 Å and 2.69 eV for MgSnN₂ in the disordered rocksalt structure compare well with experimentally reported values of 4.48 Å and 2.3 eV, respectively. Furthermore, band gaps were computed for MgSnN_2-xO_x (x = 0.5, 1.0, 1.5, 2.0) to elucidate the role of possible oxygen impurities. Band-gap bowing is suggested to occur upon alloying with oxygen. Of the three phases, the disordered rocksalt structure shows the lowest charge carrier effective masses. Moreover, the absorption coefficient and reflectivity of this phase make it promising for use as the absorber layer of tandem solar cells in the higher energy region of the visible portion of the solar spectrum. The other two phases, disordered wurtzite and orthorhombic, might be utilized as the window layer of solar cells owing to their larger band-gap values of 4.36 eV and 4.86 eV, respectively.

我们使用密度泛函理论（DFT）及其他方法通过第一原理方法研究了三元氮化物半导体MgSnN ₂的无序岩石盐，正交晶和无规纤锌矿相。结果表明，MgSnN ₂在所有三相中均具有机械和动态稳定性。然而，pCOHP分析表明，与其他两个阶段的结合状态相比，无序的岩盐结构在费米能级以下（-5 eV和-2 eV之间）具有反结合状态，表明其热力学亚稳定性。MgSnN _2的晶格常数和电子带隙值为4.56Å和2.69 eV在无序的岩盐结构中的碳纳米管与实验报告的值分别为4.48Å和2.3 eV很好。此外，计算了MgSnN _{2- x} O _x（x = 0.5、1.0、1.5、2.0）以阐明可能的氧杂质的作用。建议在与氧合金化时发生带隙弯曲。在这三个阶段中，无序的岩盐结构显示出最低的载流子有效质量。此外，该相的吸收系数和反射率使其有望在太阳光谱的可见光部分的较高能量区域中用作串联太阳能电池的吸收层。其他两个相，无序纤锌矿和正交晶，由于其较大的带隙值分别为4.36 eV和4.86 eV，因此可以用作太阳能电池的窗口层。