Highly sensitive photodetector based on transfer-free 3D graphene on SiO₂

Graphene has exceptional optoelectronic and photonic capabilities for diverse applications in solar cells, ultrafast lasers, touch screens, and photodetectors. Here, we report a graphene photodetector synthesized directly on SiO ₂ /Si substrates using the metal-organic chemical vapor deposition technique. The as-grown flake-like 3D graphene has increased surface area with numerous edge defects originating from flake edges. Additionally, the light absorption in the heavily p-doped silicon oxide/silicon (SiO ₂ /Si) substrate generates an additional photovoltage that effectively modulates the conductance of graphene, leading to high responsivity of ~114.64 A/W at a drain voltage of 15 V over a large bandwidth from visible to the near-infrared (IR) region with response and recovery time of ~7 milliseconds. In particular, the graphene photodetector achieves an external quantum efficiency (EQE) of 21702.23 % and detectivity of 1.24× 10 ¹¹ Jones at a drain voltage of 15 V. This transfer-free and scalable method can lead to low-cost and highly efficient photodetectors.