High-Responsivity,\nHigh-Detectivity, Ultrafast\nTopological Insulator Bi₂Se₃/Silicon Heterostructure\nBroadband Photodetectors

Abstract

As\nan exotic state of quantum matter, topological insulators have\npromising applications in new-generation electronic and optoelectronic\ndevices. The realization of these applications relies critically on\nthe preparation and properties understanding of high-quality topological\ninsulators, which however are mainly fabricated by high-cost methods\nlike molecular beam epitaxy. We here report the successful preparation\nof high-quality topological insulator Bi₂Se₃/Si heterostructure having an atomically abrupt interface by van\nder Waals epitaxy growth of Bi₂Se₃ films on\nSi wafer. A simple, low-cost physical vapor deposition (PVD) method\nwas employed to achieve the growth of the Bi₂Se₃ films. The Bi₂Se₃/Si heterostructure exhibited\nexcellent diode characteristics with a pronounced photoresponse under\nlight illumination. The built-in potential at the Bi₂Se₃/Si interface greatly facilitated the separation and transport\nof photogenerated carriers, enabling the photodetector to have a high\nlight responsivity of 24.28 A W^–1, a high detectivity\nof 4.39 × 10¹² Jones (Jones = cm Hz^1/2 W^–1), and a fast response speed of aproximately microseconds.\nThese device parameters represent the highest values for topological\ninsulator-based photodetectors. Additionally, the photodetector possessed\nbroadband detection ranging from ultraviolet to optical telecommunication\nwavelengths. Given the simple device architecture and compatibility\nwith silicon technology, the topological insulator Bi₂Se₃/Si heterostructure holds great promise for high-performance\nelectronic and optoelectronic applications.