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We report on the investigation of the potential application of different forms of amorphous carbon (a-C and a-C:H) as an antireflective coating for crystalline silicon solar cells. Polymeric-like carbon (PLC) and hydrogenated diamond-like carbon films were deposited by plasma enhanced chemical vapor deposition. Tetrahedral amorphous carbon (ta-C) was deposited by the filtered cathodic vacuum arc technique. Those three different amorphous carbon structures were individually applied as single antireflective coatings on conventional (polished and texturized) p-n junction crystalline silicon solar cells. Due to their optical properties, good results were also obtained for double-layer antireflective coatings based on PLC or ta-C films combined with different materials. The results are compared with a conventional tin dioxide (SnO 2 ) single-layer antireflective coating and zinc sulfide=magnesium fluoride (ZnS=MgF 2 ) double-layer antireflective coatings. An increase of 23.7% in the short-circuit current density, J sc , was obtained using PLC as an antireflective coating and 31.7% was achieved using a double-layer of PLC with a layer of magnesium fluoride (MgF 2 ). An additional increase of 10.8% was obtained in texturized silicon, representing a total increase (texturization þ double-layer) of about 40% in the short-circuit current density. The potential use of these materials are critically addressed considering their refractive index, optical bandgap, absorption coefficient, hardness, chemical inertness, and mechanical stability.

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A kinetic study of the ultrasound-stimulated and acid-catalyzed sonohydrolysis of tetraethyl orthosilicate (TEOS) in solventless TEOS-water heterogeneous mixtures was carried out by means of a calorimetric method as a function of the ultrasound power. The hydrolysis reaction starts in acidulated heterogeneous water-TEOS mixtures after an induction period under ultrasonic stimulation. The ultrasound power seems to play a role on the dynamical coupling of the system originating a continuum upward shifting of the base line during the induction period of sonication. The rate in which the base line is upward shifted diminishes with the power. The best coupling between the ultrasound and the reactant heterogeneous mixtures for this experimental setup was found to occur at 50 W, for which the gelation time was found to be a minimum. The kinetics of the heterogeneous TEOS sonohydrolysis was studied on the basis of a dissolution and reaction modeling. The heterogeneous reaction pathway as deduced from the kinetic study was drawn in a ternary diagram as a function of the ultrasound power.

The structural, surface, and thermomechanical properties of intrinsic and argon incorporated tetrahedral amorphous carbon films deposited using the filtered cathodic vacuum arc process are reported. Argon atoms were simultaneously incorporated during the deposition of the films using an argon ion gun in the energy range of 0–180 eV. Contact angle measurements revealed that all of the deposited films are hydrophobic, regardless of the substrate bias voltage that was applied during the depositions. Thermal desorption spectroscopy measurements revealed that high argon bombarding energy favors films that are structurally more compact and thermally more stable. An investigation unbinding the mechanism of argon effusion and intrinsic stress relief is presented.