Figure 2 .
Titled scanning electron microscope images of silicon pillars in square lattice. (a) Period of 2 μm with a large r/a ratio, where r is the radius of the pillars and a is the lattice period. (b) Period of 4 μm with a small r/a ratio.
Dang et al. Nanoscale Research Letters 2012 7:416 doi:10.1186/1556-276X-7-416