Alloying-engineered high-performance broadband polarized Bi_1.3In_0.7Se₃ photodetector with ultrafast response

Topological insulators have important potential for applications in the field of nano/micro-optoelectronic devices. However, the large dark current seriously hinders the improvement of device performance. Alloying is an important means to control the physical properties of topological insulators. In this work, we have designed and prepared Bi_1.3In_0.7Se₃ crystals. The optoelectronic properties of the individual Bi_1.3In_0.7Se₃ nanowire-based photodetector are systematically investigated. The photodetector is very sensitive to broadband wavelength from solar-blind ultraviolet C (254 nm) to near-infrared (1,064 nm), showing superior optoelectrical properties with photoresponsivity of 241.3 A·W^–1 and detectivity of 1.18 × 10¹² Jones at 638 nm. Furthermore, the photodetector demonstrates ultrafast photoresponse characteristics with a photoresponse time of about 770 ns, which is 3 to 6 orders of magnitude lower than other compound semiconductors based on Bi or In reported so far. In addition, it also exhibits good polarization sensitivity in a broadband range from ultraviolet C (266 nm) to near-infrared (1,064 nm) and obtained the maximum dichroic ratio is 1.73 at 1,064 nm. Our results suggest that this platform creates new opportunities for the development of low-cost, high-sensitivity, high-speed, and broadband angle-sensitive photodetectors.