Ammonothermal Synthesis and Optical Properties of Ternary Nitride Semiconductors Mg‐IV‐N₂, Mn‐IV‐N₂ and Li‐IV₂‐N₃ (IV=Si, Ge)

Abstract

Grimm-Sommerfeld analogous nitrides MgSiN , MgGeN , MnSiN , MnGeN , LiSi N and LiGe N (generally classified as II-IV-N and I-IV -N ) are promising semiconductor materials with great potential for application in (opto)electronics or photovoltaics. A new synthetic approach for these nitride materials was developed using supercritical ammonia as both solvent and nitride-forming agent. Syntheses were conducted in custom-built high-pressure autoclaves with alkali metal amides LiNH , NaNH or KNH as ammonobasic mineralizers, which accomplish an adequate solubility of the starting materials and promote the formation of reactive intermediate species. The reactions were performed at temperatures between 870 and 1070 K and pressures up to 230 MPa. All studied compounds crystallize in wurtzite-derived superstructures with orthorhombic space groups Pna2 (II-IV-N ) and Cmc2 (I-IV -N ), respectively, which was confirmed by powder X-ray diffraction. Optical bandgaps were estimated from diffuse reflectance spectra using the Kubelka-Munk function (MgSiN : 4.8 eV, MgGeN : 3.2 eV, MnSiN : 3.5 eV, MnGeN : 2.5 eV, LiSi N : 4.4 eV, LiGe N : 3.9 eV). Complementary DFT calculations were carried out to gain insight into the electronic band structures of these materials and to corroborate the optical measurements.

Solid Solutions of Grimm–Sommerfeld Analogous Nitride Semiconductors II‐IV‐N2 (II=Mg, Mn, Zn; IV=Si, Ge): Ammonothermal Synthesis and DFT Calculations

“…Due to the mixed‐occupancy sites in solid solutions, DFT calculations are challenging without relying on extensive supercell calculations. Previous works on mixed‐occupancy CaMSiN 3 (M=Al, Ga) materials and fully ordered II‐IV‐N 2 materials were successfully used to describe the electronic structure in the framework of the Korringa–Kohn–Rostoker (KKR) Green's function method together with bandgap corrections by the Engel–Vosko formalism . Here we advance the described method to show successful application to solid solutions of these nitride materials.…”

“…However, the bulk synthesis of these materials is still challenging. Recently, we employed the ammonothermal method as a suitable synthetic approach to Zn‐IV‐N 2 compounds (IV=Si, Ge), as well as other Grimm–Sommerfeld analogous nitrides such as II‐IV‐N 2 (II=Mg, Mn; IV=Si, Ge), II 2 ‐P‐N 3 (II=Mg, Zn), CaGaSiN 3 , and Ca 1− x Li x Al 1− x Ge 1+ x N 3 ( x ≈0.2) . By employing this method, we were able to synthesize crystalline ZnSiN 2 and ZnGeN 2 with crystal sizes of several micrometers and, for the first time, single crystals of Mg 2 PN 3 with lengths of up to 30 μm.…”

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase EuIIEuIII2Ta2N4O3

“…Subsequently, the autoclave was heated to the respective reaction temperature within 6 h and kept at this temperature for 110 h. The pressure slowly decreased over time because of hydrogen loss of the autoclave. Further details of the used autoclaves can be found in literature , , , …”

Crystalline Nitridophosphates by Ammonothermal Synthesis

“…[1][2][3][4][5] The ammonothermal technique gainedf undamentali nterest in materials science as it facilitates the growth of high-quality GaN single crystalsu pt o 50 mm in diameter with growth rates of several hundred mm per day. [10][11][12][13][14][15] Applyingt he ammonothermal technique, even the challenging preparation of afew nitridophosphates has been accomplished successfully as reportedf or K 3 P 6 N 11 andt he double nitrides Mg 2 PN 3 and Zn 2 PN 3 . [10][11][12][13][14][15] Applyingt he ammonothermal technique, even the challenging preparation of afew nitridophosphates has been accomplished successfully as reportedf or K 3 P 6 N 11 andt he double nitrides Mg 2 PN 3 and Zn 2 PN 3 .…”