Effect of Al-induced gettering and back surface field on the efficiency of Si solar cells
In silicon solar cell fabrication, impurity gettering from Si by an aluminum layer and indiffusion of Al for creating the back surface field (BSF) are inherently carried out in the same process. We have modeled these two processes and analyzed their impact on solar cell efficiency. The output of gettering and Al indiffusion modeling is used as an input for calculation of solar cell efficiency. The cell efficiency gain is obtained as a function of the processes duration. To check the relative contributions of gettering and BSF in improving the cell efficiency, their effects are evaluated together as well as separately. It is found that, for solar cells fabricated from low quality, multicrystalline Si, the efficiency gain is solely due to gettering. In solar cells made of high quality Si, the efficiency gain is primarily due to gettering, but the BSF may play a significant role if the cell thickness is less than about 200 μm. The two effects are found to be synergetic. The model provides a means for optimization of the temperature regime for both processes, as well as for maximization of solar cell efficiency. © 2001 American Institute of Physics.
Plekhanov, PS; Negoita, MD; Tan, TY
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