Quantum Plasmonic-Grating Enhanced Topological Heterojunction for Broadband Photodetection

Topological insulators continue to be promising candidates for broadband photodetection owing to their robust surface states and superior optoelectronic properties. Here, an advanced heterojunction photodetector composed of p-type Sb₂Te₃ and n-type Bi₂Te₃ is reported, whose performance is significantly enhanced through the integration of plasmonic grating electrodes. The plasmonic gratings concentrate the incident electromagnetic field at the heterojunction interface, thereby promoting a stronger generation of photocarriers and reducing the carrier transit time (Wang & Du, 2016). As a result, the modified device exhibits an enhanced photocurrent density of 7.68 mA cm⁻², an improved responsivity of 42.67 mA W⁻¹, and a detectivity of 1.478 × 10⁹ Jones. Moreover, the incorporation of plasmonic structures accelerates the photoresponse time by a factor of five relative to devices without such enhancement. These performance improvements underline the feasibility of employing topological insulator heterojunctions, in combination with plasmonic engineering, for applications in optical communications, high-speed electronics, and next-generation optoelectronic systems.