Composition, Structure, and Semiconducting Properties of MgxZr2-xN2 Thin Films

Synthesis and characterization of Mg _x Zr_2-xN₂ (0.5 ≤ x ≤ 1.8) thin films deposited by reactive magnetron co-sputtering in nitrogen plasma is reported. Composition measurements show that nitrides with low oxygen content (less than 1%) can be formed up to x = 1.0, at which point an increase in oxygen content is observed. Up to composition of x = 1.6 the Mg _x Zr_2-xN₂ thin films form in a rocksalt-derived crystal structure, as revealed by X-ray diffraction measurements. At x > 1.6 the films rapidly oxidize. The lattice constant of the stoichiometric MgZrN₂ composition is a = 4.537 Å, and only small changes in lattice parameter are observed with changing composition. Electrical conductivity decreases by several orders of magnitude with increasing Mg-content. The conductivity of Mg-rich (x ≥ 1) films increases with increasing measurement temperature, indicating semiconducting character of Mg-rich Mg _x Zr_2-xN₂. Optical absorption measurements of these Mg-rich samples show a clear absorption onset at 1.8 eV, also indicative of semiconducting behavior.