Synthesis of CaSnN₂ via a High-Pressure Metathesis Reaction and the Properties of II-Sn-N₂ (II = Ca, Mg, Zn) Semiconductors

Abstract

A novel ternary nitride semiconductor, CaSnN2, with a layered rock-salt-type structure (R3̅m) was synthesized via a high-pressure metathesis reaction. The properties and structures of II-Sn-N2 (II = Ca, Mg, Zn) semiconductors were also systematically studied, and the differences among them were revealed by comparison. These semiconductor materials showed a rock-salt- or wurtzite-type structure depending on the combined effect of the synthetic conditions and the characteristics of the group II elements. Additionally, the rock-salt-type structures of CaSnN2 and MgSnN2 (i.e., the ambient-pressure phase) were different from those predicted using first-principles calculations. Further, on the basis of first-principles calculations and consideration of the pressure effect, the recovered CaSnN2 sample showed an R3̅m structure. CaSnN2 and MgSnN2 showed a band gap of 2.3–2.4 eV, which is suitable for overcoming the green-light-gap problem. These semiconductors also showed a strong cathode luminescence peak at room temperature, and generalized gradient approximation (GGA) calculations revealed that CaSnN2 has a direct band gap. These inexpensive and nontoxic semiconductors (II-Sn-N2 semiconductors (II = Ca, Mg, Zn)), with mid band gaps are required as pigments to replace cadmium-based materials. They can also be used in emitting devices and as photovoltaic absorbers, replacing In x Ga1–x N semiconductors.

Synthesis and Characterization of the Ternary Nitride Semiconductor Zn2VN3: Theoretical Prediction, Combinatorial Screening, and Epitaxial Stabilization

“…Strikingly, nitrides remain a rather underexplored class of materials, − in part due to their challenging synthesis. For example, as the formation of the corresponding oxide phases is energetically often more favorable, the synthesis of nitrides often requires particularly clean or highly energetic synthesis environments. , The enormous potential of this phase space was recently demonstrated in a comprehensive high-throughput computational study by Sun et al through the prediction of hundreds of new stable and metastable ternary metal nitrides .…”

Band Gap-Tunable (Mg, Zn)SnN2 Earth-Abundant Alloys with a Wurtzite Structure

“…Recently, we experimentally identified an analogous compound CaSnN 2 with E g = 2.3 eV and a green-light cathode luminescence at room temperature. 42 The band gap (E g ) tunability of Zn−(IV,IV′)−N 2 alloys, such as Zn(Si,Ge)N 2 and Zn(Ge,Sn)N 2 , has also been investigated. The E g values of ZnSiN 2 and ZnGeN 2 are 4.5 and 3.2 eV, 8 respectively (Figure 1b), and thus, the Zn(Si,Ge)N 2 alloys are wide-gap semiconductors having E g values of 3.2−4.5 eV.…”

“…The cations in the sputtered ZnSnN 2 and MgSnN 2 films almost randomly occupy the cation sublattice in the wurtzite structure (disordered wurtzite structure), , as shown in Figure a (the crystal structure was visualized using the software VESTA). Recently, we experimentally identified an analogous compound CaSnN 2 with E g = 2.3 eV and a green-light cathode luminescence at room temperature . The band gap ( E g ) tunability of Zn–(IV,IV′)–N 2 alloys, such as Zn­(Si,Ge)­N 2 and Zn­(Ge,Sn)­N 2 , has also been investigated.…”

Two-step solid-state synthesis of ternary nitride materials

“…For thin film applications, nitrogen plasma (N • ) can be employed to deposit ternary metal nitrides ranging from rocksalt magnesium metal nitrides, such as MgZrN 2 and Mg 2 NbN 3 , 9,10 to wurtzite zinc metal nitrides such as Zn 2 SbN 3 and Zn 3 MoN 4 . 11,12 In bulk powder form, ternary nitrides have been synthesized by high pressure metathesis, 13,14 ammonolysis, 15 ammonothermally, 16 and from the elements under flowing N 2 . 17 For the ambient-pressure synthesis of magnesium metal nitrides, lower temperatures are required to avoid the loss of Mg from the ternary products.…”

“…The presented reaction conditions are benign and can be performed in a traditional solid-state chemistry laboratory, thus increasing their utility in targeting new metal nitride compositions by multiple research groups. Previous studies on the synthesis of magnesium metal nitrides have employed custom high-pressure reactors, 13,14 or specialized deposition chambers. 9,10 By starting with the mixed anion Mg 2 NCl as a precursor, the reaction pathway does not proceed via a rapid propagation, as observed when starting with more energetic precursors such as alkali azides or alkali earth nitrides 27,28 and diffusion-limited products and binary metal nitrides observed in some metathesis reactions 28,29 are avoided.…”