Directly integrated hierarchical 3D porous graphene/silicon Schottky photodetectors for self-powered operation

Graphene/Si Schottky photodetectors have exhibited significant broadband photoresponse; however, the inherently low optical absorption of graphene remains a major obstacle to the development of high-performance, scalable devices. In this work, a self-powered broadband photodetector based on a three-dimensional porous graphene (3DPG)/Si Schottky junction was demonstrated, in which the 3DPG was directly integrated onto a silicon substrate via laser-induced layer-selective graphitization. This approach enables the transfer-free formation of a hierarchical porous graphene network while simultaneously establishing a structurally and electronically integrated heterointerface, thus overcoming the limitations associated with planar graphene structures. The porous graphene architecture enhances light absorption and effective surface area, while residual oxygen-containing functional groups induce p-type doping, which increases the Schottky barrier height and strengthens the built-in electric field. As a result, the device exhibited a photocurrent approximately 20 times higher than those of planar CVD-Gr/Si devices, along with a high on/off ratio of 1.91 × 10⁵, a maximum responsivity of 1.32 A/W, and a specific detectivity of 1.57 × 10¹³ Jones at 940 nm under zero-bias conditions. These results demonstrate that the direct integration of 3DPG, combined with its simple and scalable fabrication process, provides a promising platform for high-performance, broadband, self-powered Si-based photodetectors.