Spin-Enhanced Self-Powered Light Helicity Detecting Based on Vertical WSe 2 -CrI 3 p-n Heterojunction.

Two-dimensional (2D) magnetic semiconductors offer an intriguing platform for investigating magneto-optoelectronic properties and hold immense potential in developing prospective devices when they are combined with valley electronic materials like 2D transition-metal dichalcogenides. Herein, we report various magneto-optoelectronic response features of the vertical hBN-FLG-CrI 3 -WSe 2 -FLG-hBN van der Waals heterostructure. Through a sensible layout and exquisite manipulation, an hBN-FLG-CrI 3 -FLG-hBN heterostructure was also fabricated on identical CrI 3 and FLGs for better comparison. Our results show that the WSe 2 -CrI 3 heterostructure, acting as a p - n heterojunction, has advantageous capability in light detection, especially in self-powered light helicity detecting. In the WSe 2 -CrI 3 heterojunction, the absolute value of photocurrent I PH exhibits obvious asymmetry with respect to the bias V , with the I PH of reversely biased WSe 2 -CrI 3 p-n heterojunction being larger. When the CrI 3 is fully spin-polarized under a 3 T magnetic field, the reversely biased WSe 2 -CrI 3 heterojunction exhibits advantageous capability in light helicity detecting. Both the short-circuit currents I SC and I PH show one-cycle fluctuation behaviors when the quarter-wave plate rotates 180°, and the corresponding photoresponsivity helicities can be as high as 18.0% and 20.1%, respectively. We attribute the spin-enhanced photovoltaic effect in the WSe 2 -CrI 3 heterojunction and its contribution to circularly polarized light detection to the coordination function of the spin-filter CrI 3 , the valley electronic monolayer WSe 2 , and the spin-dependent charge transfer between them. Our work helps us understand the interplay between the magnetic and optoelectronic properties of WSe 2 -CrI 3 heterojunctions and promotes the developing progress of prospective 2D spin optoelectronic devices.