A model for oxidation kinetics in air at room temperature of hydrogen-terminated (1  ) Si

Cerofolini, G. F.; Mascolo, Daniele Di; Vlad, Marcel Ovidiu

doi:10.1063/1.2245191

Cited by 31 publications

(45 citation statements)

References 35 publications

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“…46 The absence of SiO x signals is despite the fact that all of the surface modification steps downstream from SAM-1 are done in the presence of water; even though oxygen has a key role in the oxidation reaction of the surface it is water molecules that are known to catalyze this reaction. 47 This is a very encouraging result for future applications of these surfaces. Fig.…”

Section: Redox Constructs Incorporating Amide Links (Sam-5a)mentioning

confidence: 59%

The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

Ciampi

James

Choudhury

et al. 2013

Phys. Chem. Chem. Phys.

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. (2013). The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes. Physical Chemistry Chemical Physics, 15 (24), 9879-9890.The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes AbstractIn this paper we explore a multi-step synthetic strategy toward fabrication of monolayer-modified Si(100) electrodes that can be electrochemically switched. The synthetic scheme is modular and benefits from an established intramolecular lactonization scheme of benzoquinone analogs. A redox-tagged pendant group can be released from the surface such as to allow for in situ monitoring of the switch process. We show that this model system can be used to elucidate chemical and structural events for a surface dynamic system that is rapidly gaining popularity. The influence of polarization times, overpotentials and semiconductor doping type on the kinetic of the switch event is also investigated. In both basic and acidic aqueous electrolytes the release of suitable redox-active markers is found to require unexpectedly large cathodic overpotentials. The release event is accompanied by minor oxidation of the electrode surface and the switched constructs can be regenerated by chemical means with no appreciable deterioration of surface quality. 2013 the Owner Societies. The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes † Simone Ciampi, a Michael James,z b Moinul H. Choudhury, a Nadim A. Darwish a and J. Justin Gooding* aIn this paper we explore a multi-step synthetic strategy toward fabrication of monolayer-modified Si(100) electrodes that can be electrochemically switched. The synthetic scheme is modular and benefits from an established intramolecular lactonization scheme of benzoquinone analogs. A redox-tagged pendant group can be released from the surface such as to allow for in situ monitoring of the switch process. We show that this model system can be used to elucidate chemical and structural events for a surface dynamic system that is rapidly gaining popularity. The influence of polarization times, overpotentials and semiconductor doping type on the kinetic of the switch event is also investigated.In both basic and acidic aqueous electrolytes the release of suitable redox-active markers is found to require unexpectedly large cathodic overpotentials. The release event is accompanied by minor oxidation of the electrode surface and the switched constructs can be regenerated by chemical means with no appreciable deterioration of surface quality.

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Section: Redox Constructs Incorporating Amide Links (Sam-5a)mentioning

confidence: 59%

The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

Ciampi

James

Choudhury

et al. 2013

Phys. Chem. Chem. Phys.

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“…This is followed by electron transfer from the broken bond to an adsorbed O 2 molecule, which drifts toward the cleaved bond, leading to the oxidation of this bond and of a neighboring Si-Si bond. 45 The sequence of steps involved in the ambient-air oxidation of Si-NCs can be seen in reference [25]. The steps prior to the formation of Si-O-Si take place during the induction period and a larger amount of surface Si-OH groups results in a shorter t m .…”

Section: 29mentioning

confidence: 99%

“…For ambient-air oxidation of bulk-Si surfaces, values ranging from 3 to 170 h have been found, depending on the Si surface index, air humidity, and the initial amount of residual Si-OH groups at the surface. [37][38][39][40][41] According to the Cabrera-Mott mechanism of ambient-air oxidation of bulk-Si and Si-NC surfaces, 20,33,45 the oxidation is initiated by adsorption of water molecules at surface Si-OH groups followed by cleavage of Si-Si backbonds of Si-OH. This is followed by electron transfer from the broken bond to an adsorbed O 2 molecule, which drifts toward the cleaved bond, leading to the oxidation of this bond and of a neighboring Si-Si bond.…”

Section: 29mentioning

confidence: 99%

Freestanding silicon nanocrystals with extremely low defect content

et al. 2012

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The future exploitation of the exceptional properties of freestanding silicon nanocrystals (Si-NCs) in marketable applications relies upon our ability to produce large amounts of defect-free Si-NCs by means of a low-cost method. Here, we demonstrate that Si-NCs fabricated by scalable RF plasmaassisted decomposition of silane with additional hydrogen gas injected into the afterglow region of the plasma exhibit immediately after synthesis the lowest reported defect density, corresponding to a value of only about 0.002-0.005 defects per NC for Si-NCs with 4 nm in size. In addition, the virtually perfect hydrogen termination of these Si-NCs yields an enhanced resistance against natural oxidation in comparison to Si-NCs with nearly one order of magnitude larger initial defect density.

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“…5,19 This is the mechanism considered earlier in the description of the ambient air oxidation of bulk-Si surfaces, i.e. in the simultaneous presence of water and oxygen molecules, 55 and is schematically represented in Fig. 6.…”

Section: 54mentioning

confidence: 99%

“…After this, an electron is transferred from the broken bond to an adsorbed O 2 molecule (step 3) and the resulting electrostatic potential forces the O − 2 to drift towards the cleaved Si-Si bond (step 4), leading to the oxidation of this bond and of a neighboring Si-Si bond (step 5). 55 The latter step involves initially the formation of a disilperoxo bridge Si-O-O-Si, which is subsequently transformed in the two Si-O-Si groups via the Bartlett's butterfly mechanism. 55 Within the mechanism represented in Fig.…”

Section: 54mentioning

confidence: 99%

Oxidation of freestanding silicon nanocrystals probed with electron spin resonance of interfacial dangling bonds

et al. 2011

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The oxidation of freestanding silicon nanocrystals (Si-NCs) passivated with Si-H bonds has been investigated for a wide range of oxidation times (from a few minutes to several months) by means of electron spin resonance (ESR) of dangling bonds (DBs) naturally incorporated at the interface between the NCs core and the developing oxide shell. These measurements are complemented with surface chemistry analysis from Fourier-transform infrared spectroscopy. Two surface phenomena with initiation time thresholds of 15 minutes and 30 hours are inferred from the dependence of ESR spectra on oxidation time. The first initiates before oxidation of surface Si-Si bonds and destruction of the NCs hydrogen termination takes place (induction period), and results in a decrease of the DBs density and a localization of the DBs orbital at the central Si atom. Within the Cabrera-Mott oxidation mechanism, we associate this process with the formation of intermediate interfacial configurations, resulting from surface adsorption of water and oxygen molecules. The second surface phenomenon leads to a steep increase of the defects density and correlates with the formation of surface Si-O-Si bridges, lending experimental support to theoretically proposed mechanisms for interfacial defect formation involving the emission of Si interstitials at the interface between crystalline Si and the growing oxide.

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A model for oxidation kinetics in air at room temperature of hydrogen-terminated (1 ) Si

Cited by 31 publications

References 35 publications

The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

The detailed characterization of electrochemically switchable molecular assemblies on silicon electrodes

Freestanding silicon nanocrystals with extremely low defect content

Oxidation of freestanding silicon nanocrystals probed with electron spin resonance of interfacial dangling bonds

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