High aspect ratio photo-assisted electro-chemical etching of silicon and its application for the fabrication of quantum wires and photonic band structures

A photo-assisted electro-chemical etching technique has recently been developed by Lehmann for the fabrication of porous silicon and highly anisotropic trenches in silicon. The discovery of room temperature photo-luminescence of porous silicon and its suitability for the fabrication of photonic band structures has stimulated a large interest in the development of silicon as an optical material. We have developed the anodic etching technique for the fabrication of quantum wires and photonic band structures. We discuss the electro-chemical process in detail, and report the successful fabrication of a photonic band structure based on macro-porous silicon. The band structure shows a band gap for the H-polarisation state between 2.78 μm and 6.25 μm