Effect of debris on the silicon wafering for solar cells

Christophe Ballif, Adrien Bidiville
Elsevier, 2011
Article

The wafers used by the photovoltaic industry are mostly produced by multi-wire slurry sawing. One of the key factors determining the wafer quality (presence of saw marks and chips, increased roughness, wafer thickness variations and wafer strength) is the abrasive slurry. For cost reduction, the slurry is regularly exchanged and the debris it contains is removed in a recycling operation. To optimise the slurry usage, it is of utmost importance to understand the effects of the silicon debris concentration in the slurry. This was studied by sawing several bricks one after the other with the same slurry. It was found that when the amount of debris is too high (more than 4% of the slurry volume), saw marks appear on the wafers and they become more fragile. Finally, a first qualitative model explaining the apparition of the saw marks and the reduction of wafer strength is proposed. (C) 2011 Elsevier B.V. All rights reserved.

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Concepts associés

Chargement

Publications associées

Chargement

Christophe Ballif, Adrien Bidiville
Elsevier, 2011
Article

Résumé

Official source

https://infoscience.epfl.ch/record/171155?ln=fr

À propos de ce résultat

Concepts associés (9)

Concepts associés

Chargement

Publications associées (4)

Publications associées

Chargement

, ,

Reducing the wafer breakage rate without changing the wafer thickness and sawing thinner wafers while maintaining constant breakage rate are two possibilities to decrease the costs of solar cells. They are similar in the sense that both require stronger wafers. To achieve this goal, it is important to gain insight into the wire-sawing process, its underlying defect creation mechanisms and the impact of sawing parameters on wafer strength. Consequently, a series of bricks were sawn with different slurry densities, wire tensions and feed rates, and the results were analyzed in terms of the wafer strength measured by bending tests. Roughness and wafer thickness were also measured. It is found that the strongest wafers were obtained by using a low abrasive volume fraction in the slurry, a low wire tension and a slow feed rate. From the analyses, we provide a qualitative interpretation of the effects of the processes at work in slurry-based wafering that explains, for instance, the wafer thickness and roughness variations. Based on physical arguments about the interaction between the wire, the silicon carbide particles and the silicon wafer, a semi-empirical model relating defect creation to the sawing parameters is developed. With this model, the wafer strength distribution can be predicted, thus simplifying optimization of the sawing process. (C) 2014 Elsevier B.V. All rights reserved.

Elsevier2015

Chargement

FeOx magnetization enhancing E-coli inactivation by orders of magnitude on Ag-TiO2 nanotubes under sunlight

Stefanos Giannakis, Juan Kiwi, Arnaud Magrez, Marco Mangayayam, César Pulgarin, Sami Rtimi, Ivica Zivkovic

Drastic bacterial enhancement was observed when the Ag(3%)-TiO2 nanotubes were modified with FeOx (3%) magnetic oxide. On bare TiO2- nanotubes a reduction of 0.21og(10)CFU was observed within one hour under simulated low intensity solar light. Under similar conditions, a bacterial reduction of 2.5log(10)CFU was observed, on Ag(3%)TiO2 increasing to 6.0log(10)CFU on Ag(3%)-TiO2-FeOx(3%) magnetic nanotubes. The bacterial inactivation kinetics is strongly influenced by the addition of FeOx. The fast inactivation induced by the composite catalyst seems to involve an increase in the interfacial charge transfer (IFCT) compared to a 2-oxide composite photocatalyst. Stable recycling of the photocatalyst was observed leading to bacterial oxidation. The unambiguous identification of the radical intermediates: OH-radicals, O-singlet and the valence holes vb(h +) on the Ag-TiO2-FeOx interface showed that the valence band holes vb(h +) were the main oxidative intermediates leading to bacterial inactivation. Nanotubes size, crystallinity and bulk composition of magnetite 1% (0 = 51.0 degrees), anatase 5% (0 = 8.9 degrees), goethite 37.3% (0 = 9.0 degrees), silver 1% (0=2.7 degrees) was obtained by the Rietveld refinement for the Ag(3%)-TiO2-FeOx(3%) nanotubes. The redox chemistry during bacterial inactivation was determined by X-ray photoelectron spectroscopy (XPS). (C) 2016 Elsevier B.V. All rights reserved.

Elsevier2017

Chargement

Duality in the Escherichia coli and methicillin resistant Staphylococcus aureus reduction mechanism under actinic light on innovative co-sputtered surfaces

Myriam Koumba Sarah Ballo, Juan Kiwi, Danièle Laub, César Pulgarin, Sami Rtimi, Rosendo Sanjines

The kinetics of bacterial reduction of Staphylococcus aureus (MRSA) on co-sputtered TiO2/Cu-polyester (TiO2/Cu-PES) was found to be little dependent on the applied light dose. But in the case of Escherichia coil, the bacterial reduction kinetics was observed to be strongly dependent on the applied light dose. The reasons for the different effect of the applied light dose on the bacterial reduction are discussed. Mechanistic considerations are suggested to account for this observation.TiO2/Cu-PES obtained by direct current magnetron co-sputtering and the bacterial reduction features compared to PES sputtered individually by TiO2 and Cu. This study presents the first evidence for the stabilizing effect of TiO2 on the amounts of the Cu released during bacterial inactivation by co-sputtered surfaces compared to sequential sputtering of Ti and/or Cu on PES. The release of Cu-monitored in the ppb range by inductively coupled plasma-mass spectrometry (ICP-MS) is indicative of an oligodynamic effect leading to bacterial reduction. The bacterial reduction of MRSA ATCC 43300 on co-sputtered TiO2/Cu led to a 5 log(10) (99.999%) reduction within 120 min in the dark and 60 min under low intensity actinic light. Diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and X-ray fluorescence (XRF) describe the TiO2/Cu surfaces investigated in this study. (C) 2015 Elsevier B.V. All rights reserved.

Elsevier2015

Chargement

Cellule photovoltaïque

Une cellule photovoltaïque, ou cellule solaire, est un composant électronique qui, exposé à la lumière, produit de l’électricité grâce à l’effet photovoltaïque. La puissance électrique obtenue est pro

Wafer

En électronique, un wafer (littéralement en français « tranche ») est une tranche ou une plaque très fine de matériau semi-conducteur monocristallin utilisée pour fabriquer des composants de microéle

Slurry

droite|vignette| Une suspension composée de billes de verre dans de l'huile de silicone s'écoulant dans un plan incliné Une boue (en slurry) est un mélange de solides plus denses que l'eau, en suspen