Self-powered Ag-nanowires-doped graphene/Si quantum dots/Si heterojunction photodetectors

Abstract

We report Ag-nanowires (Ag NWs)-doped graphene/p-type SiO2-embedded Si quantum dots (p-SQDs:SiO2)/n-Si heterojunction photodetectors (PDs). It is found that the p-n junctions show excellent PD characteristics including photocurrent/dark current (on/off) ratio of 105 at 0 V bias, meaning “self-powered”. The PDs optimized at an Ag NWs concentration of 0.1 wt % exhibit 0.32–0.65 AW-1 responsivity (R), ∼85% external quantum efficiency (EQE), and ∼4.5 × 1012 cm Hz1/2/W detectivity in the visible range of 500–900 nm. The linear dynamic range and response time of the PDs at 532 nm are ∼83 dB and ∼2 μs, respectively. The loss of the R is only 15% of its initial value while the PDs are kept for 700 h in air. In particular, the EQE of the self-powered PD is comparable to that of commercially-available Si PD and better than those of previously-reported graphene/Si PDs. These results suggest that the doped graphene/p-SQDs:SiO2/n-Si heterojunctions are promising for their applications in self-powered optoelectronic devices.