The investigation on the quality of aluminum rear emitter for n-type solar cells

Since rear emitter characterization is the crucial factor for aluminum back junction n-type cells, the emphasis of this paper is focused on the quality of this Al-Si alloy layer. Diffusion profile test is used to describe the diffusion of Al in the silicon rear side. It is found that the Al-Si alloy layer´s thickness of about 6 μm should be better. In order to get a thicker thickness, a higher temperature or a slow belt velocity is needed in the firing process. However, it is found that a higher temperature is not suitable, which will cause a higher concentration of Al atoms in the layer. A lower firing speed almost only thickens the alloy layer. A high Voc of 650 mV and a high fill factor of 0.818 have been obtained by slowing down the firing speed.