Fabrication of size-selected bimetallic nanoclusters using magnetron sputtering

Copper-tin (Cu_xSn_1-x) nanocluster is a promising system for gas sensing applications, mainly because of its sensitivity and selectivity for H2S. In this work, pure Sn and Cu as well as composite Cu _xSn_1-x nanoclusters were synthesized using the dc magnetron sputtering gas condensation technique. Nanoclusters with different Sn to Cu ratios were produced by changing the ratio of Sn and Cu in the target. The dependence of Sn, Cu, and Cu_xSn_1-x nanoclusters' size distribution on various source parameters, such as the inert gas flow rate and aggregation length, has been investigated in detail. The results show that as the inert gas flow rate increases, the mean nanocluster size increases for Sn, decreases for Cu, while increases and then decreases for Cu_xSn _1-x. The results could be understood in terms of the contribution percentage of the nanocluster formation mechanism. Furthermore, this work demonstrates the ability of tuning the Cu_xSn_1-x nanoclusters' size and composition by a proper optimization of the source operation conditions.