Structure of Porous Si Formed by Metal-Particle (Pt, Pd) Enhanced HF Etching

Abstract

Metal-particle-enhanced HF etching of Si can produce micrometer-sized macroporous and nanometer-sized microporous Si by simple immersion of metal-particle-modified Si in a HF aqueous solution without a bias or a particular oxidizing agent. The etching rate of Si and the structure of produced porous Si are changed by the dissolved oxygen concentration of the HF solution and the photoillumination intensity on Si during etching. In this study, we found that strong photoillumination promotes the etching of Pt-modified n-Si under the absence of dissolved oxygen in the HF solution. Pd particles show a unique behavior in which the etching of n-Si proceeds at a high rate accompanying hydrogen evolution under dark conditions and the absence of dissolved oxygen.