Porous Silicon Formation by Stain Etching

Kołasiński, Kurt W.

doi:10.1007/978-3-319-05744-6_4

Cited by 4 publications

(3 citation statements)

References 130 publications

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“…Following the patterning, the devices were exposed to stain etch solutions. While there are many stain etch chemistries, in this work the etch chemistry based on V 2 O 5 /HF was chosen due to its simple setup and rapid etch rates. − …”

Section: Experimental Setupmentioning

confidence: 99%

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Porous Nanophotonic Optomechanical Beams for Enhanced Mass Adsorption

et al. 2019

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We have developed a porous silicon nanocantilever for a nano-optomechanical system (NOMS) with a universal sensing surface for enhanced sensitivity. Using electron beam lithography, we selectively applied a V 2 O 5 /HF stain etch to the mechanical elements while protecting the silicon-on-insulator photonic ring resonators. This simple, rapid, and electrodeless approach generates tunable device porosity simultaneously with the mechanical release step. By controlling the porous etchant concentration and etch time, the porous etch depth, resonant frequency, and the adsorption surface area could be precisely manipulated. Using this control, cantilever sensors ranging from nonporous to fully porous were fabricated and tested as gas-phase mass sensors of volatile organic compounds coming from a gas chromatography stream. The fully porous cantilever produced a dramatic 10-fold increase in sensing signal and a 6-fold improvement in limit of detection (LOD) compared to an otherwise identical nonporous cantilever. This signal improvement could be separated into mass responsivity increase and adsorption increase components. Allan deviation measurements indicate that a further 4-fold improvement in LOD could be expected upon speeding up characteristic peak response time from 1 s to 50 ms. These results show promise for performance enhancement in nanomechanical sensors for applications in gas sensing, gas chromatography, and mass spectrometry.

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Section: Experimental Setupmentioning

confidence: 99%

“…However, these methods are not applicable for structures devoid of electrodes (as in our case) wherein the mass sensor is based on a nanophotonics platform made from silicon-on-insulator. Stain etching has an advantage over electrode etching methods as it does not require electrodes.…”

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confidence: 99%

Porous Nanophotonic Optomechanical Beams for Enhanced Mass Adsorption

et al. 2019

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“…Traditional porous silicon is a thin film of solid silicon and voids, usually made by anodization. Electroless etching facilitates the formation of such traditional porous silicon thin films [2][3][4] as well as powders [5]. However, when combined with an array of metal nanoparticles or holes in a metal film, stain etching can produce a forest of nanowires or an array of macropores [4,[6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Electron transfer during metal-assisted and stain etching of silicon

Kołasiński

2015

Semicond. Sci. Technol.

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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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