Ternary Nitride Semiconductors in the Rocksalt Crystal Structure

TL;DR

This paper introduces a new class of ternary nitride semiconductors with rocksalt structures, demonstrating their promising optoelectronic properties through experimental synthesis and theoretical analysis.

Contribution

It reports the discovery and characterization of rocksalt-structured ternary nitrides as semiconductors, expanding the known material classes beyond wurtzite nitrides.

Findings

Mg-rich compositions are nondegenerate semiconductors with visible-range absorption

Epitaxial MgZrN₂ shows high electron mobility (~100 cm²V⁻¹s⁻¹)

Theoretical calculations indicate tunable optical properties and low effective masses

Abstract

Inorganic nitrides with wurtzite crystal structures are well-known semiconductors used in optoelectronic devices. In contrast, rocksalt-based nitrides are known for their metallic and refractory properties. Breaking this dichotomy, here we report on ternary nitride semiconductors with rocksalt crystal structures, remarkable optoelectronic properties, and the general chemical formula Mg$_{x}$TM$_{1-x}$N (TM=Ti, Zr, Hf, Nb). These compounds form over a broad metal composition range and our experiments show that Mg-rich compositions are nondegenerate semiconductors with visible-range optical absorption onsets (1.8-2.1 eV). Lattice parameters are compatible with growth on a variety of substrates, and epitaxially grown MgZrN$_{2}$ exhibits remarkable electron mobilities approaching 100 cm$^{2}$V$^{-1}$s$^{-1}$. Ab initio calculations reveal that these compounds have disorder-tunable optical properties, large dielectric constants and low carrier effective masses that are insensitive to disorder. Overall, these experimental and theoretical results highlight Mg$_{G-3}$TMN$_{G-2}$ rocksalts as a new class of semiconductor materials with promising properties for optoelectronic applications.