Ternary nitride semiconductors in the rocksalt crystal structure

Area of Science:

• Materials Science
• Solid-State Physics
• Inorganic Chemistry

Background:

• Inorganic nitrides typically exhibit either wurtzite structures (semiconductors) or rocksalt structures (superconductors/refractory materials).
• A dichotomy exists between the crystal structures and properties of inorganic nitrides, limiting their combined functionalities.

Purpose of the Study:

• To report the discovery of ternary nitride semiconductors with rocksalt crystal structures.
• To investigate their electronic and optical properties and potential applications.

Main Methods:

• Synthesis and characterization of ternary nitrides with the formula Mg_x TM _1-xN (TM = Ti, Zr, Hf, Nb).
• Experimental measurements of electronic mobility and optical absorption.
• Ab initio calculations to understand electronic band structure and disorder effects.

Main Results:

• Formation of ternary rocksalt nitrides over a broad metal composition range.
• Mg-rich compositions exhibit nondegenerate semiconducting behavior with visible-range optical absorption (1.8–2.1 eV).
• Achieved electron mobility up to 100 cm² V^-1⋅s^-1 for MgZrN₂.
• Calculations show tunable optical absorption and large dielectric constants, with bandgaps insensitive to disorder.

Conclusions:

• Mg_x TM _1-xN represents a new class of rocksalt-structured semiconductors.
• These materials combine properties of wurtzite semiconductors and rocksalt superconductors.
• Structural compatibility with existing nitride materials offers integration possibilities.