SEM images of honeycomb structures. A1-2 have a honeycomb periodicity of 2 μm, while B1-2 have a periodicity of 3 μm. A1 and B1 are surface images at 35–40° tilt. A2-B2 are cross-sectional images of a c-Si honeycomb surface structure on top of which a 5 μm nc-Si layer is grown. Red arrows in image A2 indicate cracks formed in the nc-Si phase as a result of the honeycomb surface texture.