A-15-type Nb-Si thin films prepared by co-evaporation and their atomic ordering processes

Niobium-silicon thin films are prepared by a co-evaporation technique. The crystal structure, lattice parameters, and long-range order parameter of the atoms are measured. Thin films with Si concentration near 15 at % have a single phase of A-15-type crystal structure. The maximum Si concentration of the A-15-type phase films obtained is 18 at %. The critical temperature of the Nb-Si thin films is experimentally proved to depend both on the Si concen - tration of the A-15-type phase and on the long-range order parameter. From phenomenological studies on the long-range ordering process of thin films, the order parameter is found to depend on the substrate temperature, the deposition rate, and the background gas pressure.