Cathodoluminescence and tip-plasmon resonance of Bi2Te3 triangular nanostructures

Bi 2 Te 3 , as a topological insulator, is able to support plasmonic emission in the visible spectral range. Thin Bi 2 Te 3 flakes can be exfoliated directly from a Bi 2 Te 3 crystal, and the shape of Bi 2 Te 3 flakes can be further modified by focused ion beam milling. Therefore, we have designed a Bi 2 Te 3 triangular antenna with distinct tip angles for the application of plasmonic resonance. The plasmonic emission of the Bi 2 Te 3 triangular antenna is excited and investigated by cathodoluminescence in the scanning electron microscope. Enhanced tip plasmons have been observed from distinct tips with angles of 20º, 36º, 54º, 70º, and 90º, respectively. Due to the confinement of geometric boundaries for oscillating charges, the resonant peak position of tip plasmon with a smaller angle has a blue shift. Moreover, the dependence of plasmonic behavior on the excitation position has been discovered as well. This research provides a unique approach to fabricate Bi 2 Te 3 nanostructures and manipulate the corresponding plasmonic properties.