P+-type emitters were optimized keeping the base parameters constant. Updated internal parameters were considered. The surface recombination velocity was considered variable with the surface doping level. Passivated homogeneous emitters were found to have low emitter recombination density and high collection efficiency. A complete structure p+nn+ was analyzed, taking into account optimized shadowing and metal-contacted factors for laboratory cells as function of the surface doping level and the emitter thickness. The base parameters were kept constant to make the emitter characteristics evident. The most efficient P+-type passivated homogeneous emitters, provide efficiencies around 21% for a wide range of emitter sheet resistivity (50 -- 500 omega/<img src="/img/revistas/mr/v5n4/qd.gif">) with the surface doping levels Ns=1×10(19) cm-3 and 5×10(19) cm-3. The output electrical parameters were evaluated considering the recently proposed value n i=9.65×10(9) (cm-3). A non-significant increase of 0.1% in the efficiency was obtained, validating all the conclusions obtained in this work, considering n i=1×10(10) cm-3.

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 (<FONT FACE="Symbol">h @ 21.60-21.74%)</FONT>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 <FONT FACE="Symbol">W/ <img SRC="http:/img/fbpe/mr/v4n2/n2a17fou.gif" BORDER="0"></FONT>) 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.