Ultrahigh Photoresponsivity\nEnabled by Carrier Multiplication\nin a Self-Powered Solar-Blind Photodetector Based on the WS<sub>2</sub>/Graphene Heterostructure

The\ndevelopment of high-performance, low-power solar-blind\nphotodetectors\n(SBPDs) holds significant promise for both military and civilian applications.\nCompared with wide-bandgap semiconductors, two-dimensional (2D) materials\nexhibit advantageous characteristics in the threshold and efficiency\nof carrier multiplication (CM) due to enhanced Coulomb interaction\nand relaxed momentum conservation. This allows one incident high-energy\nphoton to generate two or more electron–hole pairs effectively,\npositioning them as viable alternatives for the fabrication of high-performance\nself-powered SBPDs. Here, we have designed a vertically aligned 2D\nWS<sub>2</sub>/graphene photodetector with Au as the contact electrodes,\nforming a unilateral Schottky junction to facilitate the efficient\ntransfer of high-energy electrons generated in the WS<sub>2</sub> to\nthe graphene without thermal relaxation. This enables efficient CM\nwithin graphene, resulting in an ultrahigh responsivity of 77 mA/W\nand an external quantum efficiency of 36% at 265 nm light with zero\nbias. This work offers invaluable insights into the development of\nnext-generation SBPDs with high performance and low power consumption.