Wide-Spectrum Polarization\nDetection Based on Lattice-Induced\nPrepared Heterojunctions

Polarization photodetection has attracted much attention\nas a promising\nmethod to get more information from the target objects, and in this\nfield, two-dimensional (2D) materials with a low-symmetric structure\nshow great potential for their ability to distinguish light with different\npolarization direction. However, limited by the intrinsic crystal\nstructure and forbidden bandwidth of such materials, there are hindrances\nin optimizing polarization photodetection performance, such as improving\nthe anisotropic current ratio as well as expanding the detection spectral\nrange. Even though low-symmetric materials have been stacked through mechanical\ntransfer as a possible solution, the varying relative angles between\ndifferent materials and the pollution at the interface induced during\nthe transfer process still have negative effects on the photodetection\nperformance of these heterojunctions. In order to solve the mentioned\nproblems, a strategy to form highly low-symmetry GeSe<sub>2</sub>–GeSe\nheterojunctions by selenization of single GeSe crystals has been proposed,\nfor which the <i>b</i>-axis direction of GeSe<sub>2</sub> and the armchair direction of GeSe are spontaneously in parallel.\nThe synthesized heterojunctions with type-II energy band arrangement\ncan reach an anisotropic current ratio up to 3.5 (at 808 nm) and exhibit\na higher absorption compared to single GeSe. This work presents a\nscheme for preparing low-symmetry heterojunctions by in situ transformation,\nwhich suggests a potential approach for optimizing linearly polarized\nphotodetectors based on the designed heterojunctions’ growth.