Polarization-sensitive infrared imaging photodetectors play a crucial role in both military and civilian applications, covering night vision, airborne surveillance and environmental monitoring. Polarization-sensitive infrared photodetectors have promising applications in imaging systems and polarization sensors by virtue of the fact that they provide a new dimension of detection (light polarization state) beyond wavelength and light intensity. However, most polarization-sensitive photodetectors currently operate in the visible wavelength band, and still face many challenges in the short-wave infrared (SWIR) band for finite responsivity (R) and polarization ratio (PR).
Recently, a team of researchers from the National University of Defense Technology, South China Normal University, and the Suzhou Institute of Nanotechnology and Nano-bionanotechnology of the Chinese Academy of Sciences published a paper titled “Short-Wave Infrared Photodetectors Based on the Infrared (SWIR)” in the journal Advanced Functional Materials, according to a report by McMasters Consulting. Photodetectors Based on β-In2Se3/Te Heterojunctions for Optical Communication and Polarimetric Imaging Applications” in the journal Advanced Functional Materials. The co-first authors of the paper are Jingxian Xiong and Qiang Yu from National University of Defense Technology (NUDT), and the corresponding authors are Zhou Park and Wu Jian from NUDT, and Huo Nengjie from South China Normal University (SCNU).
This study reports a high-performance and polarization-sensitive imaging sensor in the short-wave infrared region using a vertical heterojunction β-In₂Se₃/Te. The device obtained excellent responsivity (2 A/W at 1310 nm and 0.71 A/W at 1550 nm) and specific detectivity (2.14 × 10⁹ Jones at 1310 nm and 7.3 × 10⁸ Jones at 1550 nm), which outperforms most anisotropic infrared photodetectors for 2D materials. Considering the strong anisotropy of Te nanosheets (e.g., Fig. 1), the device exhibits significant polarization-sensitive performance under 1310 nm laser irradiation, with a polarization ratio (PR) of 4.95.This study presents a multifunctional photodetector that can be used for ASCII code transmission and polarization-sensitive infrared imaging, which provides a new opportunity for multifunctional angularly-resolved photonics devices in the infrared communication band.
Fig. 1 Atomic structure and anisotropic characterization of Te nanosheets synthesized by solution method
The researchers stacked the anisotropic Te nanosheets with β-In₂Se₃ to prepare vertical heterojunction devices. In this vertical heterojunction device structure, the Te nanosheets are the carrier transport channel, and the β-In₂Se₃ layer is placed on the top of the channel as a photoresponsive top gate material. β-In₂Se₃/Te heterojunction device structure and characterization are shown in Fig. 2. To further interpret the photogating effect process in the infrared wavelength band, Fig. 2h and Fig. 2i show a schematic of the response mechanism of the device under infrared illumination
