Thermally Carbonized Porous Silicon and Its Recent Applications

Salonen, Jarno; Mäkilä, Ermei

doi:10.1002/adma.201703819

Cited by 58 publications

(42 citation statements)

References 196 publications

(303 reference statements)

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“…However, differences in their respective water contact angles provide evidence of the changing surface chemistry. THCpSi substrates presented a contact angle of 122° ± 4° while TCpSi showed a significantly lower contact angle of 31° ± 4°, which are in agreement with the hydrophobic and hydrophilic behavior of THCpSi and TCpSi, respectively, as previously reported by Salonen et al…”

Section: Resultssupporting

confidence: 91%

Porous Silicon Nanostructures as Effective Faradaic Electrochemical Sensing Platforms

Guo

Sharma

Toh

et al. 2019

Adv Funct Materials

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The electrochemical performance of porous silicon (pSi) stabilized via thermal decomposition of acetylene gas is investigated for the first time. In this study, pSi undergoes two thermal treatments at either 525 or 800 °C, which result in hydrogen-terminated thermally hydrocarbonized pSi (THCpSi) and hydroxylterminated thermally carbonized pSi (TCpSi), respectively, the latter upon dipping in hydrofluoric acid to activate the surface termination. Electrochemical characterization, using cyclic voltammetry, chronocoulometry, and electrochemical impedance spectroscopy in the presence of several redox pairs, [Fe(CN) 6 ] 3/4− , [Ru(NH 3 ) 6 ] 2/3+ , and hydroquinone/quinone, is used to demonstrate the versatility and high stability to degradation of carbon-stabilized pSi nanostructures and their excellent electrochemical performance. Added to the large surface area, adjustable pore morphology and tailorable surface chemistry of THCpSi and TCpSi, these nanostructures demonstrate fast electron-transfer kinetics, providing key advantages over conventional carbon electrodes. The versatile surface chemistry of THCpSi and TCpSi offer various possibilities to introduce multiple functional groups depending on the nature of the bioreceptor to be immobilized. For proof of principle, the use of a THCpSi-based immunosensor to detect MS2 bacteriophage is demonstrated by means of electrochemical impedance spectroscopy, showing a detection limit of 4.9 pfu mL −1 . Carbon-stabilized pSi structures represent a new class of nanostructured electrodes for biosensing applications.

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Section: Resultssupporting

confidence: 91%

Porous Silicon Nanostructures as Effective Faradaic Electrochemical Sensing Platforms

Guo

Sharma

Toh

et al. 2019

Adv Funct Materials

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“…There has been intense interest in the use of carbonization to passivate PS films. Carbonization can be achieved through a number of wet and gas‐based processes, with the use of acetylene at 600 °C being the most widely used approach for carbonization of an entire film. The carbonization process ensures the pores remain open and clear, maintaining the large surface after thermal treatment.…”

Section: A Comparison Of Laser Writing Approaches Involving Porous Mamentioning

confidence: 99%

“…Subsequently, the films were immersed in AZ326 developer containing in 1% KOH, typically used during microelectronics processing of positive photoresists. The ability to survive such chemical immersions is an important test of the robustness of the passivation . Immersion in KOH stripped the unpassivated PS from the surface leaving bare silicon and laser written features.…”

Section: A Comparison Of Laser Writing Approaches Involving Porous Mamentioning

confidence: 99%

“…Subsequent wet processing using HF immersion provides a simple method to define the passivated carbonized features as shown in Figure . The carbonized PS is expected to have a larger Young's modulus than as‐fabricated PS, relatively unchanged optical characteristics, and good electrical properties . All these properties are important for the fabrication of freestanding, electrically‐actuated MEMS sensors which require strong, thin films patterned to contain microscale features which enable them to be insensitive to inertial (gravitational) effects .…”

Section: A Comparison Of Laser Writing Approaches Involving Porous Mamentioning

confidence: 99%

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Selective Oxidation and Carbonization by Laser Writing into Porous Silicon

Keating

Sun

2018

Adv Materials Technologies

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The selective formation of either oxidized or carbonized features into 2.5 µm thick porous silicon (PS) films using laser writing at a wavelength of 405 nm is demonstrated. Oxidized features are formed in air while carbonized features are achieved during the flow of propane at 600 sccm. Voids which have been previously associated with the use of propane are not observed, largely due to the rapid heating and high flow rates achieved in the experiment. Carbonized regions with feature widths down to 1.8 µm are achieved and chemical resistance to both hydrofluoric acid and potassium hydroxide is demonstrated. Once carbonized regions are formed, the surrounding areas can be overwritten in air to convert the surrounding regions into oxidized PS allowing films to be created with as‐fabricated, oxidized and carbonized regions. Energy dispersive X‐ray and Raman analysis confirms the presence of carbon within the written structures. At high optical powers, cracking around the carbonized features is observed which is attributed to a contraction of the film. Such cracking is not observed during selective oxidation of features. This work significantly enhances the ability to engineer and pattern the composition of PS films enabling selective control of the material's properties and functionality.

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“…Chen and Du (2014) studied a lithium lanthanum titanate as a promising solid electrolite-not experimentally but by molecular dynamics and atomistic computer simulations. Salonen and Mäkilä (2018) note applications of porous silicon in areas as diverse as luminescence, drug delivery and battery technology. Braun et al (2018) have developed a method of fabrication of entropy-stabilized ceramics with low thermal conductivity while mechanically strong at the same time.…”

Section: Introduction and Scopementioning

confidence: 99%

Scratch Testing of Hard Ceramics: Manifestation of Viscoelasticity

Brostow¹,

Hnatchuk²,

Prażuch³

2019

JMSR

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Viscoelasticity is studied extensively in polymers and polymer-based composites-but hardly in ceramics. We have studied viscoelastic behavior of three ceramics as manifested in scratching tests: 98 weight % B 4 C + 2% hexagonal boron nitride (h-BN), 92% B 4 C and 8% h-BN, 91% B 4 C + 5% CrSi 2 + 2% h-BN. Clear viscoelastic recovery (the groove depth becoming shallower within 2 minutes) is seen in all three materials, the recovery in each case of at least 90%. Taking into account viscoelasticity and introducing appropriate additives, one could significantly improve the scratch resistance of the boron carbides, and possibly of other hard ceramics as well.

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Thermally Carbonized Porous Silicon and Its Recent Applications

Cited by 58 publications

References 196 publications

Porous Silicon Nanostructures as Effective Faradaic Electrochemical Sensing Platforms

Porous Silicon Nanostructures as Effective Faradaic Electrochemical Sensing Platforms

Selective Oxidation and Carbonization by Laser Writing into Porous Silicon

Scratch Testing of Hard Ceramics: Manifestation of Viscoelasticity

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