Figure 6.

Optical properties and ultimate efficiencies of core-shell nanoparticles with different t placed on the rear side of the 2 μm thick Si substrates with different P. The inner Au core is 120 nm and the n is set as 3.4. (a) Absorption enhancement factor of core-shell nanoparticle when compared with the 2 μm thick Si with 120 nm Au sphere and a flat cell (P = 400 nm, t = 60 nm). (b) Ultimate efficiency of core-shell nanoparticles on the 2 μm thick Si. (c) Differential efficiency ∆η between the core-shell nanoparticles on a 2 μm flat Si and a 2 μm flat Si without nanoparticles. The dashed line is the differential value between the core-shell nanoparticles on a 2 μm thick Si and a 120 nm Au sphere on a 2 μm thick Si and the P is set as 400 nm; the inset is the schematic in simulation.