EELS imaging analysis of surface plasmon polaritons confined in silicon cluster superlattice

Silicon cluster superlattices, which have been generated by direct deposition of a silicon cluster beam with a monodisperse size distribution, give a just solution to bring forth new functional nanomaterials consistent with a sustainable society. Silicon clusters correctively form a unclosed-packed body centered cubic (bcc) superlattice structure with a lattice constant of 2.134±0.002 nm, retaining a sp 3 diamond structure of the same lattice constant as in crystalline silicon (c-Si). The sp 3 structures are spread uniformly across the superlattice and the endogenous surfaces on the silicon clusters successively form a topologically new nanostructure. The low-loss EELS spectra with a 60 keV probing electron beam have demonstrated surface plasmon losses in the energy range 3.0 eV ≤ E, along with an intense peak at 16.5 eV of the bulk plasmon losses in c-Si. The results are consistent with the analytical results of the endogenous surface Tamm states with a metallic electronic structure. The characteristic surface plasmon loss peaks appearing at even intervals of nearly 1 eV reveal that each incident probing electron absorbs multi-quanta nħω (n = 1, 2, 3, .., 10) from surface plasmons localized in the silicon cluster superlattice. Silicon cluster superlattices possibly clear a path to Nanophotonic Silicon in future photonics.