Growth of magnesium nitride thin films on various surfaces via atomic-nitrogen-assisted molecular beam epitaxy at moderate substrate temperatures

We report on the growth of Mg3N2 thin films via atomic-nitrogen-assisted molecular beam epitaxy (MBE) on various surfaces, i.e., silicon, sapphire, and gallium nitride surfaces, near room temperature. At moderate substrate temperatures, the effective growth rate of the Mg3N2 film via atomic-nitrogen-assisted MBE is an interplay between condensation of the Mg atoms on the substrate surface, nitridation of the deposited Mg atoms, re-evaporation of the deposited Mg atoms, and-in case of silicon substrates-formation of magnesium silicide. After exploring the growth parameters on Si(100), we obtained amorphous and (poly)crystalline Mg3N2 thin films and also applied these growth parameters to Si(111), Al2O3(0001), and GaN(0001) surfaces. The observed strong sensitivity of the nitride film to ambient conditions implies that a protective capping layer is required, for which we relied on a thick Mg coating deposited in situ. Mg3N2 is a direct band gap material that can be considered as a potential material candidate for integration in electronic and optical applications, provided that an adequate capping layer to prevent degradation in ambient is used.

Automated summary

In this study, Mg3N2 thin films were grown on various surfaces using atomic-nitrogen-assisted molecular beam epitaxy (MBE). The growth rate of the Mg3N2 film was found to depend on the condensation, nitridation, re-evaporation, and formation of Mg silicide on the substrate surface. The growth parameters were optimized to obtain amorphous and (poly)crystalline Mg3N2 thin films on different surfaces. A protective capping layer of thick Mg coating was necessary due to the sensitivity of the nitride film to ambient conditions.