An ultrafast and self-powered MoSSe/Si photodetector with high light-trapping structures and a SiO interface layer.

MoSSe nanofilms, as a typical metal dichalcogenide, have attracted great interest, due to their adjustable bandgap and distinctive electronic and optical properties. However, the inherent bandgap of MoSSe and the strong interface recombination impede the actualization of a high-sensitivity photodetector (PD). Few-layer MoSSe nanofilms were prepared with vertically orientation at 450 °C, which would be a less restrictive choice of substrates. Herein, a self-powered MoSSe/SiO/Si photodetector was fabricated which exhibits unprecedented performance with excellent reproducibility and stability from 405 nm to 980 nm, a high responsivity (0.450 A W), normalized detectivity (4.968 × 10 Jones) and ultrafast photoresponse ( = 1.20 μs, = 4.92 μs) at zero bias under 980 nm incident laser illumination with a density of 200 μW cm. Significantly, the self-powered PD is capable of detecting ultraweak IR signals below 200 μW cm with high on-off ratios. More importantly, an oxidized atomic layer is generated through the wet oxidation in the Piranha solution. The PD can work well at high frequencies even at 100 kHz, which shows its potential application in high-frequency photoelectric devices and health monitors. Summing up, this work not only suggests that an ultrathin SiO interface layer can reduce carrier recombination simple interface engineering, but also proposes a novel strategy for the preparation of high-performance and low-cost optoelectronic devices.