Topological insulator bismuth selenide grown on black phosphorus for sensitive broadband photodetection

Abstract

The photovoltaic characteristics of high-quality Bi₂Se₃ grown on black phosphorus (BP) heterostructure via modulated elemental reactants (MER, annealed in situ at 220 °C for 20 min in a vacuum of 10⁻⁹ torr) growth of a Bi₂Se₃ topological insulator (TI) film on an exfoliated BP two-dimensional (2D) nanosheet was investigated. The Bi₂Se₃/BP heterostructure showed high-efficiency photocharacteristics (responsivity: 12.1 mA W⁻¹, rise time: 1.3 ms, and broadband detection range: λ = 350–950 nm), which are attributed to the narrow band gap of the bulk state and mobility of the Dirac surface state. Moreover, the Bi₂Se₃/BP heterostructure can produce heterojunctions in the sharp interface region, thereby resulting in the contribution of a strong built-in electric field and photoexcited carrier tunnel through the interactive interfacial region at the TI/2D heterostructure based on the photovoltaic device. This work demonstrates practical photovoltaic applications, as well as the integration of such TIs on 2D materials, which can offer great opportunities for the realization of next-generation optoelectronic devices.