Routes of Formation for Porous Silicon

The etching of silicon in fluoride solutions is limited by the kinetics of charge transfer not thermodynamics. This characteristic is what gives fluoride etching its great versatility in making different types of nanostructures as the result of self-limiting chemistry. This review approaches the kinetics of electron transfer from silicon and metal coated silicon to a solution phase species from a fundamental point of view in order to establish a better understanding of the mechanisms of nanostructure formation during metal assisted and stain etching of silicon. Band bending calculations demonstrate that diffusion of holes away from low work function metals such as Ag is not possible. Similarly diffusion of holes outside of the space charge layer is not possible for high work function metals such as Au, Pd and Pt. While direct hole injection may be important for etch track pore formation in the immediate vicinity of the metal, the charge imbalance on or near the metal causes the metal to act like a nanopower supply that polarizes the surrounding Si. This second mechanism is implicated in nonlocal etching of Si during metal assisted etching. KEYWORDS silicon nanowires, metal assisted etching, metal nanoparticles, stain etching, porous silicon, surface chemistry, electron transfer.

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Routes of Formation for Porous Silicon

Cited by 6 publications

References 35 publications

Synthesis Gallium Nitride on Porous Silicon Nano-Structure for Optoelectronics Devices

Synthesis Gallium Nitride on Porous Silicon Nano-Structure for Optoelectronics Devices

Room-temperature fabrication of a three-dimensional porous silicon framework inspired by a polymer foaming process

Electron transfer during metal-assisted and stain etching of silicon

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