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This work focuses on studying two types of structure: homogeneous and double-diffused emitter silicon solar cells. The emitter collection efficiencies and the recombination current densities were studied for a wide range of surface dopant concentrations and thicknesses. The frontal metal-grid was optimized for each emitter, considering the dependence on the metal-semiconductor contact resistivity and on the emitter sheet resistance. The best efficiency for n + p structures, η ≈ 25.5%, is found for emitters with thicknesses between (0.5-3) µm and surface doping concentrations in the range 2 x 10 19 cm -3 -4 x 10 18 cm -3 ; while the n ++ n + p structure a maximum efficiency of η ≈ 26.0% was identified for an even wider range of emitter profiles.

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Considering recent modifications on n-type highly doped silicon parameters, an emitter optimization was made based on one-dimensional models with analytical solutions. In order to get good accuracy, a fifth order approximation has been considered. Two kinds of emitters, homogeneous and non-homogeneous, with phosphorus Gaussian profile emitter solar cells were optimized. According to our results: homogeneous emitter solar cells show their maximum efficiencies (h @ 21.60-21.74%)with doping levelsnus = 1x10(19) - 5x10(18) (cm-3) and (1.2-2.0) mum emitter thickness range. Non-homogeneous emitter solar cells provide a slightly higher efficiency (eta = 21.82-21.92%), with Ns = 1x10(20) (cm-3) with 2.0 mum thickness under metal-contacted surface and Ns = 1x10(19) - 5x10(18) (cm-3) with (1.2-2.0) mum thickness range, (sheet resistance range 90-100 W/ ) under passivated surface. Although non-homogeneous emitter solar cells have a higher efficiency than homogeneous emitter ones, the required technology is more complex and their overall interest for practical applications is questionable

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