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

Abstract

Grimm–Sommerfeld analogous II‐IV‐N2 nitrides such as ZnSiN2, ZnGeN2, and MgGeN2 are promising semiconductor materials for substitution of commonly used (Al,Ga,In)N. Herein, the ammonothermal synthesis of solid solutions of II‐IV‐N2 compounds (II=Mg, Mn, Zn; IV=Si, Ge) having the general formula (IIa 1−xIIb x)‐IV‐N2 with x≈0.5 and ab initio DFT calculations of their electronic and optical properties are presented. The ammonothermal reactions were conducted in custom‐built, high‐temperature, high‐pressure autoclaves by using the corresponding elements as starting materials. NaNH2 and KNH2 act as ammonobasic mineralizers that increase the solubility of the reactants in supercritical ammonia. Temperatures between 870 and 1070 K and pressures up to 200 MPa were chosen as reaction conditions. All solid solutions crystallize in wurtzite‐type superstructures with space group Pna21 (no. 33), confirmed by powder XRD. The chemical compositions were analyzed by energy‐dispersive X‐ray spectroscopy. Diffuse reflectance spectroscopy was used for estimation of optical bandgaps of all compounds, which ranged from 2.6 to 3.5 eV (Ge compounds) and from 3.6 to 4.4 eV (Si compounds), and thus demonstrated bandgap tunability between the respective boundary phases. Experimental findings were corroborated by DFT calculations of the electronic structure of pseudorelaxed mixed‐occupancy structures by using the KKR+CPA approach.

Facile One‐step Synthesis of Zn1–xMnxSiN2 Nitride Semiconductor Solid Solutions via Solid‐state Metathesis Reaction

“…The observed absorption bands in the spectra of ZnSiN 2 and MnSiN 2 were primarily attributed to direct transitions due to the similarity of direct and indirect bandgaps in the materials , . Direct transitions for the solid solutions were assumed according to previously reported DFT calculations . The bandgap of the boundary phases ZnSiN 2 (3.7 eV), and MnSiN 2 (3.4 eV) are well between the range expected from literature,, and the bandgap of the solid solution Zn 1– x Mn x SiN 2 is linearly decreasing with increasing x .…”

“…Secondly, ZnSiN 2 has been synthesized as deposited thin films by metalorganic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE) techniques . Thirdly, ZnSiN 2 is accessible by an ammonothermal approach using super‐critical ammonia as the solvent at 600 °C in custom made autoclaves , …”

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 .…”

“…Recent explorative syntheses under ammonothermal conditions made crystalline wurtzite‐type Grimm–Sommerfeld analogous nitrides available, such as InN, II‐IV‐N 2 compounds (II=Mg, Mn, Zn; I V =Si, Ge) and CaGaSiN 3 , as well as oxide nitride perovskites such as LnTaON 2 (Ln=La, Ce, Pr, Nd, Sm, Gd) . Applying the ammonothermal technique, even the challenging preparation of a few nitridophosphates has been accomplished successfully as reported for K 3 P 6 N 11 and the double nitrides Mg 2 PN 3 and Zn 2 PN 3 .…”

Ammonothermal Synthesis of Ba2PO3N – An Oxonitridophosphate with Non‐Condensed PO3N Tetrahedra

“…InN, II‐IV‐N 2 (II = Mg, Mn, Zn; IV = Si, Ge), CaGaSiN 3 or Ca 1– x Li x Al 1– x Ge 1+ x N 3 ( x ≈ 0.2)] and oxide nitride perovskites [e.g. EAM O 2 N ( EA = Sr, Ba; M = Nb, Ta)] as well . Most recently, the syntheses of numerous nitridophosphates with different degrees of condensations κ (i.e.…”