High-performance position-sensitive detector based on graphene–silicon heterojunction

Position-sensitive detectors (PSDs) based on the lateral photo effect have been widely used in diverse applications including optical engineering, aerospace, and military fields. With increasing demands for long-working-distance, low-energy-consumption, and weak-signal-sensing systems, the poor responsivity of conventional silicon-based PSDs has become a bottleneck limiting their applications. Herein, we propose a high-performance passive PSD based on a graphene–Si heterostructure. The graphene is adapted as a photon-absorbing and charge-separation layer working together with Si as a junction, while the high mobility provides promising ultra-long carrier diffusion length and facilitates a large active area of the device. A PSD with a working area of 8  mm×8  mm is demonstrated to present excellent position sensitivity to weak light at the nanowatt level (much better than the limit of microwatts of Si P-I-N PSDs). More importantly, it shows very fast response and low degree of nonlinearity of ∼3%, and extends the operating wavelength to the near-infrared region (1319 and 1550 nm). This work therefore provides a new strategy for high-performance and broadband PSDs.