Scattering-type Near-Field Optical Microscopy Characterization of Topological Insulator Bi2Te3 nanowires

Topological Insulator (TI) devices have potential applications in spintronic and low-loss communication devices. However, they are difficult to characterize with standard far-field spectroscopy due to contributions from both the surface and the bulk. Utilizing the surface-sensitive scattering type Scanning Nearfield Optical Microscopy (s-SNOM) technique coupled with high surface-to-volume ratio structures such as nanowires, the local dielectric function and electro-optical properties of the metallic surface states of TI candidate Bi
2
Te
3
are investigated. We demonstrate spectral resonant features at 1250 cm $^{-1}$, which are imaged with nanoscale resolution.