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

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.