Study of amorphous Zinc Germanium Nitride thin films grown by reactive co-sputtering

Under its crystalline form, the ZnGeN2 alloy is promising for optoelectronic devices such as LEDs because of its large, direct and adjustable band gap. Nevertheless, data are scarce, more especially for the amorphous form. We report here on the study of zinc germanium nitride amorphous thin films obtained by reactive co-sputtering. The samples are elaborated by PVD and analyzed by physical and chemical methods to determine their composition, structure and optical properties. We observe a clear evolution of these properties with composition. The shape of the complex refractive index reveals changes in the electronic structure. Furthermore, the optical gap and Urbach energy decrease with increasing zinc content.