Size-dependent of plasmonic gold nanoparticles enhanced on WS₂/Si nanohybrids photodetector

Metallic nanostructures play a role in many applications owing the ability of supporting surface plasmons and enhanced device performance from the manipulation and flexibility of size dependence. Herein, we optimized the plasmonic metallic nanostructures of gold nanoparticles (AuNPs) on nanohybrid structures of AuNPs embedded on tungsten disulphide (WS₂) using p-type silicon substrate. Three different thicknesses layer of Au namely 6 nm, 8 nm and 10 nm has been deposited using electron beam evaporation machine before undergoing thermal annealing process at 600 °C for 1 min for nanoparticles formation. Particles with average size of 40 nm, 60 nm and 85 nm evolved accordingly to the thickness layer. Spray pyrolysis technique of WS₂ was applied on the AuNPs before depositing gold contact for nanohybrid photodetector. We observe that the 6 nm thickness Au nanofilms that form 40 nm AuNPs average particle sizes exhibit the optimum surface plasmon resonance which increase the light absorption, scattering and localized electromagnetic field of incoming light compared to bare WS₂. The Au(6 nm)-WS₂ device has the highest responsivity of 1.91 A/W and specific detectivity of 1.15 × 10¹¹ Jones compared to bare WS₂ device that exhibit lower responsivity and specific detectivity of 1.19 A/W and 6.58 × 10¹⁰ Jones, respectively. The response time for Au (6 nm)-WS₂ and bare WS₂ device are 6.00 ms and 4.64 ms, respectively. We report high performance Au NPs enhanced WS₂ photodetector under the illumination of 532 nm light.