Electron spectroscopy study in the NbN growth for NbN/AlN interfaces

NbN superconductor and wide band gap AlN thin films were deposited using sputtering at room temperature. Study of the nitride interfaces are forerunner to the growth Josephson junctions that are considered able to work in the terahertz frequency. We find that to be compatible with lithography technology and to have a high critical transition temperature, the substrate should not be overheated, and this means working in low power regime to limit the induced heating of the plasma. X-ray photoelectron spectroscopy and X-ray diffraction analysis were performed on samples deposited on crystalline, amorphous, flexible, and nanostructured substrates. The experimental results suggest us how to improve the deposition process in order to obtain the best nitride films as well as NbN/AlN/NbN trilayers for Josephson junction applications.