Abstract
In this study, the efficient generation of terahertz radiation by a dipole photoconductive antenna, based on a thin island film of a topological insulator, was experimentally demonstrated. The performance of the Bi1.9Sb0.1Te2Se antenna was shown to be no worse than those of a semiconductor photoconductive antenna, which is an order of magnitude thicker. The current–voltage characteristics were studied for the photo and dark currents in Bi1.9Sb0.1Te2Se. The possible mechanisms for generating terahertz waves were analyzed by comparing the characteristics of terahertz radiation of an electrically biased and unbiased topological insulator.
Highlights
Topological insulators (TIs) are considered to be promising new 2D materials for terahertz (THz) generators and detectors [1,2,3]
We demonstrated a working photoconductive antenna with a dynamic range of order of 60 dB based on the nanofilm of the topological insulators (TIs) Bi2−x Sbx Te3−y Sey
In addition to the known nonlinear effects, the photoconductive mechanism of THz generation was realized in TIs because of the relaxation of bulk electrons through the surface states
Summary
Topological insulators (TIs) are considered to be promising new 2D materials for terahertz (THz) generators and detectors [1,2,3]. TIs are characterized by the presence of stable (topologically protected against backscattering), conducting surface states of an electronic gas. In addition to ARPES, there are other methods that are sensitive to edge electronic states. In [8], a new method was proposed for detecting the surface states of electrons based on the photo-electromagnetic effect (PEM), which is not sensitive to bulk conductivity. The generation of THz radiation can be sensitive to surface electron transfer. Hamh et al demonstrated a circular anisotropy of the photon drag effect (PDE) in Bi2 Se3 , which proves optical coupling with topological surface states [10]
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