On the mechanism ruling the morphology of silicon nanowires obtained by one-pot metal-assisted chemical etching

Magagna, Stefano; Narducci, Dario; Alfonso, Claude; Dimaggio, Elisabetta; Pennelli, Giovanni; Charaı̈, A.

doi:10.1088/1361-6528/ab9b47

Cited by 7 publications

(17 citation statements)

References 39 publications

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“…Silicon nanowire forests have been fabricated by a simple and inexpensive process based on one-pot metal-assisted chemical etching (MACE) [ 22 ] ( Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…Silicon nanowire forests have been fabricated by a simple and inexpensive process based on one-pot metal-assisted chemical etching (MACE) [22] (Figure 1). Silicon chips of roughly 1 × 1 cm 2 have been cut from n-doped (phosphorous) commercial silicon ⟨100⟩ wafers with a nominal resistivity of 10 Ω•cm (nominal doping concentration 10 15 cm −3 ).…”

Section: Fabrication and Doping Of Silicon Nanowire Forestsmentioning

confidence: 99%

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Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Elyamny¹,

Dimaggio²,

Pennelli³

2020

Beilstein J. Nanotechnol.

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Thermoelectric generators made by large arrays of nanowires perpendicular to a silicon substrate, that is, so-called silicon nanowire forests are fabricated on large areas by an inexpensive metal-assisted etching technique. After fabrication, a thermal diffusion process is used for doping the nanowire forest with phosphorous. A suitable experimental technique has been developed for the measurement of the Seebeck coefficient under static conditions, and results are reported for different doping parameters. These results are in good agreement with numerical simulations of the doping process applied to silicon nanowires. These devices, based on doped nanowire forests, offer a possible route for the exploitation of the high power factor of silicon, which, combined with the very low thermal conductivity of nanostructures, will yield a high efficiency of the conversion of thermal to electrical energy.

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“…Silicon nanowire forests have been fabricated by a simple and inexpensive process based on one-pot metal-assisted chemical etching (MACE) [ 22 ] ( Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

Section: Fabrication and Doping Of Silicon Nanowire Forestsmentioning

confidence: 99%

Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Elyamny¹,

Dimaggio²,

Pennelli³

2020

Beilstein J. Nanotechnol.

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“…Also the material removal patterns, even for the much simpler planar silicon geometries are a matter of controversial debates. [56,61,[73][74][75][76] In fact, it appeared to us that one important aspect has been completely ignored so far in the MACE literature, namely a potential attraction of the AgNP to the silicon oxide that is forming at the AgNP/silicon interface. Since the pH value in the MACE process is larger than the isoelectric point of silica (pH iso =3.9), the Si-OH groups of this interface are partially deprotonated.…”

Section: Evolution Of Hierarchical Porosity In Macroporous Silicon By...mentioning

confidence: 99%

Wafer‐Scale Fabrication of Hierarchically Porous Silicon and Silica by Active Nanoparticle‐Assisted Chemical Etching and Pseudomorphic Thermal Oxidation

Gries¹,

Brinker²,

Zeller‐Plumhoff³

et al. 2023

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Many biological materials exhibit a multiscale porosity with small, mostly nanoscale pores as well as large, macroscopic capillaries to simultaneously achieve optimized mass transport capabilities and lightweight structures with large inner surfaces. Realizing such a hierarchical porosity in artificial materials necessitates often sophisticated and expensive top‐down processing that limits scalability. Here, an approach that combines self‐organized porosity based on metal‐assisted chemical etching (MACE) with photolithographically induced macroporosity for the synthesis of single‐crystalline silicon with a bimodal pore‐size distribution is presented, i.e., hexagonally arranged cylindrical macropores with 1 µm diameter separated by walls that are traversed by pores 60 nm across. The MACE process is mainly guided by a metal‐catalyzed reduction–oxidation reaction, where silver nanoparticles (AgNPs) serve as the catalyst. In this process, the AgNPs act as self‐propelled particles that are constantly removing silicon along their trajectories. High‐resolution X‐ray imaging and electron tomography reveal a resulting large open porosity and inner surface for potential applications in high‐performance energy storage, harvesting and conversion or for on‐chip sensorics and actuorics. Finally, the hierarchically porous silicon membranes can be transformed structure‐conserving by thermal oxidation into hierarchically porous amorphous silica, a material that could be of particular interest for opto‐fluidic and (bio‐)photonic applications due to its multiscale artificial vascularization.

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“…The reasonable configuration for large-area nanostructured silicon thermoelectric devices consists of nanowires/nanostructures placed perpendicularly to the silicon substrate, which can be fabricated by means of maskless (no lithography), highly selective etching processes, such as metal assisted chemical etching (MACE) [ 72 , 73 ]. Very shortly, it consists in depositing metal nanoparticles, which can be gold, silver [ 74 , 75 , 76 ] and also ruthenium [ 77 ] (investigated very recently), on the top of a standard (and hence low-cost) silicon wafer. Soaking the wafer in an acqueous solution containing an oxidizing agent and HF, the silicon is locally oxidized very close to the nanoparticles (catalyzing agent) and then removed by HF.…”

Section: Techniques For All-silicon Thermoelectric Devicesmentioning

confidence: 99%

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

2021

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The potentialities of silicon as a starting material for electronic devices are well known and largely exploited, driving the worldwide spreading of integrated circuits. When nanostructured, silicon is also an excellent material for thermoelectric applications, and hence it could give a significant contribution in the fundamental fields of energy micro-harvesting (scavenging) and macro-harvesting. On the basis of recently published experimental works, we show that the power factor of silicon is very high in a large temperature range (from room temperature up to 900 K). Combining the high power factor with the reduced thermal conductivity of monocrystalline silicon nanowires and nanostructures, we show that the foreseen figure of merit ZT could be very high, reaching values well above 1 at temperatures around 900 K. We report the best parameters to optimize the thermoelectric properties of silicon nanostructures, in terms of doping concentration and nanowire diameter. At the end, we report some technological processes and solutions for the fabrication of macroscopic thermoelectric devices, based on large numbers of silicon nanowire/nanostructures, showing some fabricated demonstrators.

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On the mechanism ruling the morphology of silicon nanowires obtained by one-pot metal-assisted chemical etching

Cited by 7 publications

References 39 publications

Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Seebeck coefficient of silicon nanowire forests doped by thermal diffusion

Wafer‐Scale Fabrication of Hierarchically Porous Silicon and Silica by Active Nanoparticle‐Assisted Chemical Etching and Pseudomorphic Thermal Oxidation

Silicon Nanowires: A Breakthrough for Thermoelectric Applications

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