Analysis of emitter performance contacted with silicide induced dopant segregation

The emitter in silicon solar cells has to fulfill two contrary conditions: a high surface doping concentration is required in order to allow ohmic contact formation. At the same time, however, the surface doping concentration should be small in order to suppress Auger recombination and decrease the surface recombination. Selective emitter structures have been proposed to resolve this trade-off but realizations so far either are not self-aligned exhibiting a rather large highly doped area where recombination can occur, or the emitter doping profile cannot be optimized without jeopardizing ohmic contact formation. Using nickel silicidation induced dopant segregation we were recently able to show that almost any emitter can be contacted due to collecting the dopants at the silicide/silicon interface. As a result, the emitter can be optimized in terms of low Auger and surface recombination independent of the contact formation. Here, two-dimensional simulations are carried out in order to optimize the emitter yielding highest efficiencies. We find that deep, rather lowly doped emitters and relatively large distances of adjacent front-side contacts result in a substantial performance increase.