Self-aligned local contacts through a-Si:H passivation layer

A novel method forms less than 100 μm wide self-aligned local contacts through an amorphous silicon based passivation layer stack on crystalline silicon solar cells. Wire shading during the plasma deposition of the passivation layer enables local contact formation without the use of photolithography or laser processes. Subsequent full area aluminum evaporation and thermal annealing create good electrical contacts. The structure combines a low effective surface recombination velocity 36 cm/s and high implied open circuit voltage 715 mV with a good ohmic contact for the rear side of p-type crystalline silicon solar cells.