Comparison of Antireflective Characteristics between Square Pillar and Columned Sub-Wavelength Structures

In order to compare antireflective characteristics between square pillar and columned sub-wavelength structures (SWSs), the relationships between diffraction efficiency and major structural parameters were examined by rigorous coupled-wave analysis (RCWA) on Ge substrate. The results showed square pillar and columned SWSs all had a good antireflective property; Filling factor and structural depth were the major parameters, which affected the antireflective characteristics of SWSs; The smaller the period, the better the antireflective characteristics of SWSs; The surface shape of the SWSs had a great effect on reflectivity when filling factor or structural depth was big; Square pillar SWSs had a better antireflective characteristic than columned of SWSs when the period was big.