3D photonic crystals based on macroporous silicon: Towards a large complete photonic bandgap

Recently, a new three-dimensional photonic crystal consisting of two interpenetrating hexagonal pore sets was introduced. Here, we investigate the influence of possible experimental errors including shift, tilt and rotation of one pore set on the size of the bandgap theoretically and determine fabrication tolerances. A structure is fabricated in silicon using photo-electrochemical etching and subsequent focused ion beam milling. The change of the cross-section of the milled pores with pore depth is investigated and reflection measurements along different directions are performed indicating the low frequency edge of the photonic bandgap.