PdSe<sub>2</sub>/NbSe<sub>2</sub> Heterojunction Photodetector with Broadband Detection and Polarization Sensitivity
Can Su, Mengyang Li, Hui Yan, Yù Zhang, Heng Li, Wenhao Fan, Weijie Bai, Xinjian Liu, Qingguo Wang, Shougen Yin
Abstract
Polarized photodetectors based on anisotropic two-dimensional (2D) materials display great potential applications in communications and optoelectronics. However, the existence of high dark current, low anisotropic ratio, and response speed limits their development. In this paper, a broadband polarization angle-dependent photodetector based on the PdSe 2 /NbSe 2 van der Waals (vdW) heterojunction has been constructed. Characterization results show that the PdSe 2 /NbSe 2 heterojunction photodetector can suppress the dark current effectively (NbSe 2 ∼4 orders of magnitude and PdSe 2 ∼1 order of magnitude compared with individual material). Meanwhile, the device exhibits a broadband detection capability ranging from 405 to 980 nm. The device shows a superior responsivity of 27 mA/W, a considerable detectivity of 9.8 × 10 7 Jones, a large external quantum efficiency of 528%, and an ultrafast rise/decay time of 1.6/1.9 μs at 1 V bias under 638 nm laser wavelength. The photodetector also achieves a high polarization-sensitive anisotropic ratio of ∼2.62 under 638 nm laser irradiation. In addition, the heterojunction device shows outstanding polarization imaging capabilities, which can be used as the image sensor. This work proposed a PdSe 2 /NbSe 2 vdW heterojunction device with low dark current, broadband polarized detection, and polarized visual imaging, which will promote the development and practicality of polarization-sensitive photodetectors.