Abstract
Topological insulators, such as Bi2Te3, have been confirmed to exhibit plasmon radiation over the entire visible spectral range. Herein, we fabricate bullseye nanoemitters, consisting of a central disk and concentric gratings, on the Bi2Te3 nanoflake. Due to the existence of edge plasmon modes, Bi2Te3 bullseye nanostructures are possible to converge light towards the central disk. Taking advantage of the excellent spatial resolution of cathodoluminescence (CL) characterization, it has been observed that plasmonic behaviors depend on the excitation location. A stronger plasmonic intensity and a wider CL spectral linewidth can be obtained at the edge of the central disk. In order to further improve the focusing ability, a cylindrical Pt nanostructure has been deposited on the central disk. Additionally, the finite element simulation indicates that the electric-field enhancement originates from the coupling process between the plasmonic emission from the Bi2Te3 bullseye and the Pt nanostructure. Finally, we find that enhancement efficiency depends on the thickness of the Pt nanostructure.
Highlights
Three-dimensional topological insulators (3D TIs) have attracted dramatic interests since they perform as insulating materials in the bulk but have metallic surface states [1]
3 bullseye nanoemitter of the electron beam, we find that the plasmonic behavior of the
We investigate the plasmonic behavior of Bi2 Te3 bullseye nanoemitters, which are fabricated by focused ion beam (FIB) milling onto exfoliated Bi2 Te3 nanoflakes
Summary
Three-dimensional topological insulators (3D TIs) have attracted dramatic interests since they perform as insulating materials in the bulk but have metallic surface states [1]. Traditional plasmonic materials are mainly noble metals, such as Ag and Au [7]. These materials have been widely studied due to their strong electric field enhancements, they usually suffer from high resistive loss and low tunability [8,9]. The application of Bi2 Te3 in relative fields is significant to extend the choice of plasmonic materials beyond noble metals. The surface plasmonic radiation is available across the visible spectral range for Bi2 Te3 because ε1 ’ is negative from 240 to 798 nm [5]. Reported by Toudert et al, results of the plasmonic quality factor indicates that Bi2 Te3 is possible to have a stable plasmonic property across the visible spectral range [10]. Bi2 Te3 plasmonic nanostructures are expected to achieve numerous applications, including plasmonic lenses [12], biosensors [13], and nanoemitters [14]
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