Due to limited short-wavelength infrared (SWIR) (1.1-2.5 μm) response of silicon (Si), germanium and indium-gallium-arsenide based photodetectors have dominated the commercial market of SWIR photodetectors for decades. However, they are often constrained by high-temperature processing, spectral range, flexible incompatibility, and cryogenic cooling accessories. Therefore, it is important to develop photodetectors that can be directly integrated with complementary-metal-oxide-semiconductor devices. In this work, we demonstrate a Si-based SWIR photodetector operating in the wavelength range from 800 to 1870 nm, with responsivity up to 0.6 A/W, and operation speed down to 15 p, s. By taking advantage of the fast photo-carriers transfer between graphene (Gr) and Si-quantum-dots (QDs), along with SWIR tunable Schottky-barrier height of Gr-Si junction, a novel Schottky-PN cascade heterojunction based photodetector has been demonstrated. The hyper-boron-doped SiQDs, interacting with the Gr-Si Schottky photodiode, effectively and fast harvest SWIR-excited charge-carriers. The cascade photodiode working at room temperature, with detectivity of 1011 Jones and sensitivity of 10-13 W/Hz05, manifests a promising prospect of our Si-based SWIR photodetector.
