Size dependence of the Anderson singularity index and Seebeck coefficient of thin monodisperse nanocluster metal films

The paper presents the results of the study of thin monodisperse Co and Ta nanocluster films deposited by magnetron sputtering method onto highly oriented pyrolytic graphite (HOPG) and silicon dioxide surfaces by means of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) methods. The evolution of X-ray photoelectron spectra asymmetry of the core levels Co2p, Ta4f as the dependence on typical sizes of nanoclusters are studied. It is found experimentally that the Anderson singularity index α (i.e. asymmetry parameter) increases with decreasing of nanocluster's size. The correlation between α and Seebeck coefficient is discussed for pure bulk metals. It is shown that Seebeck coefficient of Co nanocluster films consisted of 1.2 nm sized nanoclusters can reach 120 μV/K. The applicability of the nanocluster films obtained for the development of highly efficient thermoelectric materials is discussed.