Paper EM-TuP18
The Electrical Properties of a Bimodal Nb Nanocluster Distribution Formed Through Plasma Gas Condensation

Tuesday, November 11, 2014, 6:30 pm, Room Hall D

Nanocluster growth and characterization is an expanding field of research due to the promising catalytic, electrical, magnetic, mechanical, and optical properties exhibited by these materials. The properties of nanoclusters vary from the bulk material and can be tuned by varying the nanocluster size. The ability to obtain desired nanocluster sizes and distribution is an important step in effectively utilizing these materials. Transition metal clusters have received considerable interest due to their wide range of applications. Niobium has attracted attention due to observations of ferroelectric properties at low temperature. In this work, Nb nanoclusters are deposited using a plasma gas condensation process which involves the sputtering of a Nb target to create a dense metallic vapor where clusters are formed. Changes in the nanocluster nucleation and growth are influenced through modifications of the process parameters such as carrier gas composition and flow rate, sputter source ion current, and aggregation length. The formation of a bimodal cluster distribution under select process conditions has been observed, with the smaller cluster diameter near 1 nm and the larger cluster diameter varying from 2 to 10 nm. The larger cluster forms as a simple condensation product while the smaller cluster appears to arise from a different nucleation and growth mechanism. The effects of differing argon and helium carrier gas ratios on cluster formation in conjunction with varying sputter source currents and aggregation lengths will be discussed. The effect of the cluster size on the electrical properties will be examined.