Stoichiometry and interface effects on the electronic and optical properties of SiC nanoparticles

Kassiba, A.; Makowska‐Janusik, M.; Bouclé, Johann; Bardeau, Jean‐François; Bulou, A.; Herlin, N.; Mayne, M.; Armand, X.

doi:10.1016/s0925-9635(02)00016-x

Cited by 26 publications

(19 citation statements)

References 16 publications

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“…The feature of the D1 centers was found to be consistent with that of DI centers with g = 2.0048  0.0006 observed in np-SiC obtained by the laser pyrolisis method. It was shown that DI centers disappears progressively with decreasing the degree of hexagonality of the np-SiC, which is favoured by annealing the sample [8]. Therefore, the observed small fraction of the D1 center compared to D2 center in np-SiC which have mostly cubic crystalline structure indicates that D1 center is the intrinsic defect localized in the hexagonal phase of np-SiC.…”

Section: Centermentioning

confidence: 97%

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Intrinsic defects in nonstoichiometric β-SiC nanoparticles studied by pulsed magnetic resonance methods

Савченко¹

2009

Semicond. phys. quantum electron. optoelectron.

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Nonstoichiometric -SiC nanoparticles (np-SiC) have been studied by electron paramagnetic resonance (EPR) and pulsed magnetic resonance methods including field swept electron spin echo (FS ESE), pulsed electron nuclear double resonance (ENDOR) and hyperfine sublevel correlation spectroscopy (HYSCORE). Four ESE signals related to the paramagnetic centers labeled D1, D2, D3, D4 with g = 2.0043, g = 2.0029, g = 2.0031, g = 2.0037 were resolved in FS ESE spectrum due to their different spin relaxation times. As deduced from the study of the superhyperfine structure of the D2 defect by FS ESE, pulse ENDOR and HYSCORE methods the dominant paramagnetic center is a carbon vacancy (V C) localized in -SiC crystalline phase of the np-SiC. The parameters of the D2 center coincide with those found for the V C in np-SiC obtained by laser pyrolysis method. Three other defects were identified by comparison of their EPR parameters with the microstructure of the np-SiC. The D1 defect was attributed to the V C vacancy located in -SiC crystalline phase. The D3 defect is identified with the carbon dangling bonds located in the carbon excess phase. The D4 defect was assigned to a threefold-coordinated Si atom bonded with one nitrogen atom, resulting in the formation of the local bonding Si-Si 2 N configuration in -Si 3 N 4 phase.

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Section: Centermentioning

confidence: 97%

“…Multifrequency EPR spectroscopy revealed the existence of at least three different paramagnetic intrinsic defects [2]. Two of them have been assigned to carbon vacancies located in the crystalline phases of SiC particles, and the third one was assigned to dangling bonds in excess carbon phases [8].…”

Section: Introductionmentioning

confidence: 99%

Intrinsic defects in nonstoichiometric β-SiC nanoparticles studied by pulsed magnetic resonance methods

Савченко¹

2009

Semicond. phys. quantum electron. optoelectron.

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“…the radical cations introduced by the acid doping. The difference of the linewidth between the broad and narrow lines is ascribed to the difference in the organization of the PANI chains in various regions of the sample [5,6]. Ordered regions in the polymer facilitate the mobility of polarons and their easy delocalization even by low thermal activation energy.…”

Section: Epr Spectra In Doped Pani-csa and Pani-csa-sic With A Highmentioning

confidence: 99%

“…With regard to the high specific surfaces of nanoparticles, the physical properties of hybrid nanocomposites are highly dependant on the organic-inorganic interfaces. The surface states of nanoparticles can be modified by using different synthesis conditions which monitor the stoichiometry of the surfaces, the crystalline order or the concentration of active electronic centres [5,6]. The effective control of the surface states of the nanocrystals presents an important challenge to fine-tune their physical responses of the based nanocomposites.…”

Section: Introductionmentioning

confidence: 99%

“…In this context silicon carbide (SiC) is a promising material due to its versatile behavior to adopt different crystalline polytypes which monitor the band gap as well as the electronic and optical properties [5][6][7][8]. Moreover, the surface modification of silicon carbide (SiC) nanoparticles, achieved by grafting a thin layer of semiconducting polymer with a nanometric thickness [7], represents an interesting thematic for the synthesis of original systems with new functionalities.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and optical features of silicon carbide nanoparticles and nanocomposites

Савченко¹,

Kassiba²,

Ogurtsov³

et al. 2009

2009 3rd ICTON Mediterranean Winter Conference (ICTON-MW)

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Electron paramagnetic resonance (EPR) investigations were carried out on hybrid Core-Shell nanomaterials associating silicon carbide nanoparticles and conducting polyaniline. The performed experiments compare the paramagnetic centres, the electronic transport features and the interface effects in two classes of materials, bare polymers and core-shell nanocomposites. By EPR, large doping rates were demonstrated in the bare doped polymers through important saturation phenomena which alter significantly the EPR spectrum features. Furthermore, memory effects were involved in the bare doped polymer with regard to the EPR spectrum features depending on the conditions of its thermal treatments. In the hybrid core-shell nanocomposites nor such saturation and nor memory effects were found on the EPR signals even if similar paramagnetic centres exist in both classes of samples. These behaviors were discussed taking into account the thermal stability and the doping efficiency in the considered classes of materials. Optimal doping levels were then realized and their effects on the polymers and the nanocomposites were clarified by using EPR and DRS (dielectric relaxation spectroscopy) measurements. Also, it is demonstrated that the charge carriers consist in polarons in the nanocomposites while bipolarons contributions dominate the electrical conductivity in the bare doped polymers.

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Functional Nanostructures and Nanocomposites – Numerical Modeling Approach and Experiment

Makowska‐Janusik¹,

Kassiba²

2012

Handbook of Computational Chemistry

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Stoichiometry and interface effects on the electronic and optical properties of SiC nanoparticles

Cited by 26 publications

References 16 publications

Intrinsic defects in nonstoichiometric β-SiC nanoparticles studied by pulsed magnetic resonance methods

Intrinsic defects in nonstoichiometric β-SiC nanoparticles studied by pulsed magnetic resonance methods

Electronic and optical features of silicon carbide nanoparticles and nanocomposites

Functional Nanostructures and Nanocomposites – Numerical Modeling Approach and Experiment

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