Enhancement of the quantum efficiency and stability of electroluminescence from porous silicon by anodic passivation Appl. A simple technique is described here that produces aligned curved or straight arrays of pipes. This opens the way to produce complete systems ͑electronic, photonic and fiber optic connectors͒ from silicon with large scale fabrication techniques. Our strategy in creating parallel pipes is to use high current densities ͑ϳ100 mA/cm 2 ) silicon anodization in HF solutions, in a

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... cell where the current direction and the preferential etching directions are not coincident in ͑111͒ silicon substrates. The etched structure in a nanoscale range was observed using atomic force microscopy, which shows steps. In a macroscopic scale steps were observed in the walls of arrays of tenths of millimeters diameter pipes. Pores arrays were obtained forming a ϳ90°angle with the current direction. Molecular mechanics simulations of the pipe wall structure show that a preferential etching along the ͗100͘ direction and passivation of the ͑111͒ planes are the mechanisms responsible for the formation of pore arrays structure.