Fig. 1. Experimental process

Fig. 2. SEM images. (a) SEM image of PS microsphere mask; (b) side view of moth eye structure on silicon wafer after ICP etching; (c) top view of Al₂O₃-Si structure; (d) side view of Al₂O₃-Si structure

Fig. 3. Results of spectral reflectance tests. (a) Actually measured reflectance of structure surface with different Al₂O₃ film thickness; (b) average reflectance for different Al₂O₃ film thickness

Fig. 4. Comparison of test and simulation reflectance of single structure and composite structure at 8° incidence angle

Fig. 5. Reflectance of single micro-nano structure surface and composite micro-nano structure surface (Al₂O₃ thickness of 185 nm) for P-polarization and S-polarization at incidence angle for 8°. (a) Single micro-nano structure; (b) composite micro-nano structure

Fig. 6. Electric field distributions of Al₂O₃-Si structure under different Al₂O₃ thicknesses. (a) Al₂O₃ (0 nm); (b) Al₂O₃ (100 nm); (c) Al₂O₃ (150 nm); (d) Al₂O₃ (185 nm)

Fig. 7. P-h curves of single structure and composite micro-nano structure samples obtained by different treatment methods