Galvanic porous silicon formation without external contacts

Porous silicon is usually formed under anodic polarization in an electrochemical cell. In this paper, a technique is described for forming porous silicon without using an external current or voltage source. By connecting an inert metal electrode to a silicon sample, both immersed in a HF solution, a galvanic cell is formed. Reduction of oxygen at the inert electrode results in the etching of Si at the silicon/electrolyte interface. Porous silicon is formed at a rate which is dependent on the cell current. The formation rate may be enhanced by adding oxidizing agents to the solution. Galvanic etching for forming porous Si isa promising alternative for stain etching since it gives more uniform and reproducible results. (C) 1999 Elsevier Science S.A. All rights reserved.