Flexible broadband WS₂/Si optical position-sensitive detector with high sensitivity and fast speed

Abstract

Si-based optical position-sensitive detectors (PSDs) have stimulated the interest of researchers due to their wide range of practical applications. However, due to the rigidity and fragility of Si crystals, the applications of flexible PSDs have been limited. Therefore, we presented a flexible broadband PSD based on a WS₂/Si heterostructure for the first time. A scalable sputtering method was used to deposit WS₂ thin films onto the etched ultrathin crystalline Si surface. The fabricated flexible PSD device has a broad spectral response in the wavelength range of 450–1350 nm, with a high position sensitivity of ∼539.8 mV·mm⁻¹ and a fast response of 2.3 µs, thanks to the strong light absorption, the built-in electrical field at the WS₂/Si interface, and facilitated transport. Furthermore, mechanical-bending tests revealed that after 200 mechanical-bending cycles, the WS₂/Si PSDs have excellent mechanical flexibility, stability, and durability, demonstrating the great potential in wearable PSDs with competitive performance.

Keywords

flexible / position-sensitive detectors / WS₂ heterostructure / broad spectral response / high sensitivity

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