Highly polarization sensitive infrared photodetector based on black phosphorus-on-WSe2 photogate vertical heterostructure

Abstract The ability to use infrared imaging systems with multicolor capabilities, high photoresponsivity and polarization sensitivity, is central to practical photodetectors and has been demonstrated with conventional devices based on Ⅲ-Ⅴ or Ⅱ-Ⅵ semiconductors. However, the photodetectors working at room temperature with high responsivity for polarized infrared light detection remains elusive. Here, we first demonstrate a broadband photodetector using a vertical photogate heterostructure of BP-on-WSe 2 (black phosphorus-on-tungsten diselenide) in which BP serves as the photogate and WSe 2 as the conductive channel. Ultrahigh visible and infrared photoresponsivity at room temperature can reach up to ~10 3  A/W and ~5×10 −1  A/W, respectively, and ultrasensitive visible and infrared specific detectivity is obtained up to ~10 14 and ~10 10 Jones respectively at room temperature. Moreover, the high sensitivity to infrared polarization is about 40 mA/W with incident light polarized along the horizontal axis (defined as 0° polarization). This performance is due to the strong intrinsic linear dichroism of BP and the device design which can sufficiently collect the photoinduced carriers isotropically, as well as the influence from the orientation of the edge of the BP-on-WSe 2 overlapped area which is the same for all polarizations. The high responsivity, good sensitive detectivity and highly polarization-sensitive infrared photoresponse suggest that the photodetectors based on photogate structure afford new opportunities for infrared detecting or imaging at room temperature by using two-dimensional materials.