Probing the Structural and Electronic Properties of Neutral and Anionic Lanthanum-Doped Silicon Clusters

The TM-doped Si-based semiconductor clusters have aroused increased attention in a lot of fields. Here, we have performed a structural search of the global minimum for neutral and anionic Si-n and La2Sin (n = 1-12) clusters by utilizing the efficient CALYPSO structural searching method with subsequent DFT optimization at the B3LYP level. A large population of low energetic and stable clusters is obtained, and then, the most stable isomers for different cluster sizes are confirmed in light of their total energy and PES spectra. The effect of dopants on the geometries and electronic properties of silicon clusters and their anions are investigated. It is found that the La atoms as well as charges generate distinct influences on them. In all most stable structures of La2Sin0/-, the impurity La atoms prefer the convex-capped positions of the skeleton and act as the electron donators. The analysis of stability reveals that La2Si3 with a bitriangular pyramid framework is very stable across the cluster size range of n = 1-12. The reason might be that there is pd hybridization between the Si and La atoms leading to strong Si-La bonds in the La2Si3 cluster. This finding is supported by the multicenter bonds and the Mayer bond order analysis.