The Stoichiometry of Electroless Silicon Etching in Solutions of V2O5 and HF

摘要

The etching of silicon is of fundamental importance in the manufacture of semiconductor devices, in the fabrication of microelectromechanical systems, and increasingly in materials chemistry. The wet-chemical etching of Si in HNO3/HF, an electroless electrochemical process, is an essential step in the manufacture of solar cells. When performed under conditions for the formation of porous silicon (por-Si), the process is known as stain etching. It can be initiated by a variety of more suitable oxidizing agents and can be used for the low-cost production of nanocrystalline por-Si powder or Si nanocrystals. Nonetheless, we still lack the most basic chemical understanding of this reaction: the reaction stoichiometry is unknown. Herein we conclusively report the reaction stoichiometry and interpret it fundamentally in terms of Marcus theory of electron transfer and the Gerischer model of Si etching.