Silicon solar cell emitters: Optimization and comparison of two different technologies

Considering recent modifications on n-type highly doped silicon parameters, a new 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 locally deep diffused (LDD), with gaussian profile of n(+)pp(+) solar cells were optimized. According to our results: homogeneous emitter solar cells show their maximum efficiencies (eta congruent to 21.60 - 21.74 %) with doping levels N-s = 1x10(19) - 5x10(18) (cm(-3)) and (1.2 - 2.0) mu m emitter thickness range. LDD emitter solar cells provide a slightly higher efficiency (eta = 21.82 - 21.92 %), with N-s = 1x10(20) (cm(-3)) with 2.0 mu m thickness under metal-contacted surface and N-s = 1x10(19) - 5x10(18) (cm(-3)) with (1.2 - 2.0) mu m thickness range, (sheet resistance range 90-100 Omega) under passivated surface. Although LDD 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.