Fig. 1. Model of Si nanowires. (a) 3D model; (b) simplified 2D model

Fig. 2. Schematic diagram of 2D model. (a) Si nanowire; (b) covering graphene; (c) adding Au grating

Fig. 3. Light absorption curves of device. (a) No covering graphene; (b) covering graphene

Fig. 4. Comparison of absorption curves of silicon nanowires with diameter of 120 nm with or without graphene

Fig. 5. Absorption curves of device with different graphene thicknesses

Fig. 6. Curves of device absorption with different thicknesses of Au grating. (a) Au grating thickness is 5 nm; (b) Au grating thickness is 10 nm

Fig. 7. Electric field intensity at the peak of absorption curves for devices with a diameter of 120 nm. (a) Au grating thickness is 5 nm; (b) Au grating thickness is 10 nm

Fig. 8. Curves of device absorption with different thicknesses of graphene and Au grating. (a) Au grating thickness is 5 nm; (b) Au grating thickness is 10 nm