Epitaxial Growth of Rock Salt MgZrN2 Semiconductors on MgO and GaN

Ternary nitride compound semiconductors have attracted recent attention as electronic materials since their properties can be tuned by cation stoichiometry and ordering. A recently discovered example is MgZrN₂, a ternary analog to the rock salt semiconductor ScN. MgZrN₂ has a larger bandgap and stronger dielectric response than the binary compound. Polycrystalline thin films of MgZrN₂ have been studied, but demonstration of high-quality growth is still required to establish its suitability for technological applications. Here, we report on epitaxial growth of MgZrN₂ thin films on (100) and (111) MgO substrates and (001) GaN templates. The MgZrN₂ composition is confirmed by Rutherford backscattering spectrometry, showing no oxygen in the film except for a thin surface oxide layer. Epitaxial growth results in MgZrN₂ with x-ray diffraction rocking curves with a full-width at half-maximum in the range of 0.3-3.0°, depending on the substrate. Transmission electron microscopy analysis of the MgZrN₂ film grown on a (111) MgO substrate confirms epitaxial growth and shows a sharp film/substrate interface. In-plane temperature-dependent Hall effect measurements show that the material is an n-type semiconductor with a relatively high concentration (n_300K ≈ 10¹⁹-10²⁰ cm^-3) of thermally activated electrons. Room-temperature transport measurements show a conductivity of 25 S cm^-1 and a Seebeck coefficient of -80 μV K^-1. Overall, these results provide an important step toward integration of rock salt MgZrN₂ with other technological nitrides for device applications.