Crystalline Si (c-Si) technology is dominating the photovoltaics market. These modules are nonetheless still relatively expensive, in particular because of the costly silicon wafers, which require large thickness mostly to ease handling. Thin-film technologies, on the other hand, use much less active material, exhibit a much lower production cost per unit area, but achieve an efficiency still limited on module level, which increases the total system costs. A meet-in-the-middle is possible and is the object of this paper. The development of c-Si thin-foil modules is presented: first, the fabrication of the active material on a glass module and then the processing of the Si foils into solar cells, directly on module level. The activity of IMEC in this area is put into perspective with regard to worldwide research results. It appears that great opportunities are offered to this cell concept, although some challenges still need to be tackled before cost-effective and reliable industrial production can be launched.

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acetone molecular ions retain large amounts of internal energy for more than 30 /us after formation by electron impact. (2) These highly excited ions are the dominant CID reactants at such low collision energies. (3) These low-energy (0.45-and 0.65-eV) collisions trigger the release (E -* T) of about 2.9 eV of stored energy into the recoil of the acetone ion and the collider He atom. With reference to the initial ion beam direction, the acetone ions are backward scattered and He atoms are forward scattered in the CM coordinate frame. (4) The recoiling acetone molecular ion rapidly dissociates into acetyl ion and methyl radical with low kinetic energy of separation. We infer from these observations that the collision process triggers the A -X conversion of the acetone molecular ion with the release of most (perhaps all) of the stored electronic energy as translational energy. The vibrationally excited ion then dissociates from the ground-state hypersurface. Our continuing research on polyatomic ion CID dynamics will address the question whether electronically excited states are also important intermediates at higher collision energies.

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Using a laser-induced fluorescence technique, SiF2 radicals are detected as primary gas-phase products of the chemical etching of silicon by fluorine atoms. The bending frequencies for the lower (X̃ 1A1) and the excited (Ã 1B1) state of the SiF2 molecule are determined from the observed excitation and fluorescence spectra and are in close agreement with literature. The v″2 intensity distribution of the fluorescence spectra corroborates the assignment of the upper-state vibrational levels. In a second series of experiments, the rate constant for the SiF2+F reaction at room temperature was measured: k = (5 ± 1) × 10−13 cm3 molecule−1 s−1 at pressures of 1–5 Torr helium. The absence of pressure dependence is rationalized in terms of radiative deactivation of the SiF*3 product.