Synthesis of New Nitride Alloys with Mg by Plasma-Assisted Molecular Beam Epitaxy

A great deal of work is currently devoted to the development of new semiconductor alloys that can expand the range of material properties and device applications. Although group-III nitride alloys are attractive materials owing to the wide range of tunable direct bandgaps and other suitable properties, the material choices are limited to only a few binary and ternary alloys. This situation is due in part to the limitations of the conventional deposition methods, such as chemical vapor deposition, requiring high temperature and high pressure to synthesize a wider range of metastable alloys. In this context, the synthesis of previously unreported quaternary nitride alloys including Mg—(InGaMg)N—is presented. These alloys, with a tunable bandgap and good crystallinity, extend the group of the materials that may be suitable for the fabrication of optoelectronic devices. The method is based on the conventional plasma-assisted molecular beam epitaxy (PA-MBE), using a flux-modulation technique to enable the incorporation of all elements reaching the growth surface. In addition to detailed experimental characterization of structural and optical properties of the Mg containing nitride alloys, computations on their electronic band structures are also carried out.