Self-Biased High-Responsivity\nPhotodetector Based\non a Bi₂SeTe₂ Topological Insulator

Abstract

Topological insulators\nshow promise for high-performance optoelectronic\napplications due to their nonlinear optical properties, broad spectral\nabsorption, ultrafast response to optical excitation, and excellent\nthermoelectric properties. Here, we introduce a self-biased photodetector\nbased on the topological insulator Bi₂SeTe₂,\ndriven by the photothermoelectric effect. Operating without external\nbias, the photodetector delivers a competitive visible-range photoresponse\nreaching responsivity of ≈27 mA/W and detectivity of ≈2\n× 10⁹ Jones at 458 nm. Comparable to individual topological\ninsulators as well as topological insulator-based heterojunctions,\nthis underscores Bi₂SeTe₂’s potential,\nespecially in scenarios where external power sources cannot be used.\nIts self-biased nature eliminates the need for an external bias,\nmaking it an ideal material for low-power and remote-sensing applications.