Combinatorial Synthesis of Cation-Disordered Manganese Tin Nitride MnSnN₂ Thin Films with Magnetic and Semiconducting Properties

Abstract

Magnetic semiconductors may soon improve the energy efficiency of microelectronics, but materials exhibiting these dual properties remain underexplored. Here, we report the computational prediction and realization of a new magnetic and semiconducting material, MnSnN2, via combinatorial sputtering of thin films. Grazing incidence wide-angle X-ray scattering and laboratory X-ray diffraction studies show MnSnN2 exhibits a wurtzite-like crystal structure with cation disorder. This new material has a wide composition tolerance, with a single-phase region ranging from 20% < Mn/(Mn + Sn) < 65%. Spectroscopic ellipsometry identifies an optical absorption onset of 1 eV, consistent with the computationally predicted 1.2 eV bandgap. Resistivity measurements as a function of temperature support the semiconducting nature of MnSnN2. Hall effect measurements show carrier density has a weak inverse correlation with temperature, indicating that the charge transport mechanisms are more complex than in a pristine semiconductor. Magnetic susceptibility measurements reveal a low-temperature magnetic ordering transition (≈10 K) for MnSnN2 and strong antiferromagnetic correlations. This finding contrasts with bulk, cation-ordered MnSiN2 and MnGeN2, which exhibited antiferromagnetic ordering above 400 K in previous studies. To probe the origin of this difference, we perform Monte Carlo simulations of cation-ordered and cation-disordered MnSnN2. They reveal that cation disorder lowers the magnetic transition temperature relative to the ordered phase. In addition to discovering a new compound, this work shows that future efforts could use cation (dis)order to tune magnetic transitions in semiconducting materials for precise control of properties in microelectronics.

Tolerance Factor and Phase Stability of the KCoO2-Type AMN2 Nitrides

“…In addition, it should point out that nitrides are much more covalent than oxides and that contra-polarization of electropositive A-site atoms play an important role in the structural chemistry of nitrides, which needs to be considered for the compositions for which the tolerance factors fall within the stable ranges but with the experimentally hard accessibility. At last, it should be noted that there are experimentally reported AMN 2 nitrides with the M sites occupied by the IV group elements, such as MgGeN 2 , MnSiN 2 , MgSnN 2 , – ZnSnN 2 , – MnSnN 2 . These compounds containing IV group elements in the M sites are different from the compounds containing IVB group transition metal elements.…”

Ammonothermal Crystal Growth of Functional Nitrides for Semiconductor Devices: Status and Potential

“…The two data points shown for the orthorhombic materials are the wurtzite-equivalent in-plane lattice parameters 𝑎√3 and b/2. Data were obtained from the following references: 6mm-BN [24][25][26], 6mm-AlN [18,[27][28][29], 6mm-GaN [26][27][28][29], 6mm-InN [26][27][28][29], 6mm-MnSnN2 [30], mm2-MgSiN2 [31][32][33][34][35][36], mm2-MgGeN2 [31,[33][34][35][36][37], mm2-MgSnN2 [17,33,34,[38][39][40], mm2-ZnSiN2 [21,23,[41][42][43][44], mm2-ZnGeN2 [21,23,41,42,44], mm2-ZnSnN2 [21,23,40,[44]…”

“…The Mn-II-N2 alloy system is least explored, however it is known to exhibit spin polarization (resulting in spin-specific bandgaps according to DFT calculations), as Mn introduces a magnetic moment [36]. Both cation-ordered MnSiN2 [49] and MnGeN2 [30,59] maintain anti-ferromagnetic ordering above room temperature, whereas the cation-ordered MnSnN2 shows a magnetic transition at around 10 K [30]. The order or disorder in the cation sublattice appears to play an important role in the formation of polymorphs [30].…”

“…Both cation-ordered MnSiN2 [49] and MnGeN2 [30,59] maintain anti-ferromagnetic ordering above room temperature, whereas the cation-ordered MnSnN2 shows a magnetic transition at around 10 K [30]. The order or disorder in the cation sublattice appears to play an important role in the formation of polymorphs [30]. The ordering of the heterovalent cations has also been identified as a design parameter for electronic bandgaps, which was derived via a combined experimental and theoretical study on ZnSnN2 and MgSnN2 and should be applicable to a broad group of ternary heterovalent compounds [40].…”

Penternary Wurtzitic Nitrides Li1–xZnxGe2–xGaxN3: Powder Synthesis, Crystal Structure, and Potentiality as a Solar-Active Photocatalyst

“…Mutinary wurtzitic nitrides have attracted considerable attention in recent years, owing to their potentiality for optoelectronic, photovoltaic, photocatalytic, electrochemical, and spintronic applications. − Most of them synthesized experimentally to date are restricted to ternary systems such as II–IV–N 2 and II 2 –V–N 3 , which essentially possess no compositional flexibility and, thus, limited tunability for physical properties, unless controlling the cation (dis)­order or alloying (solid-solution formation).…”