Another approach to form p+ emitter for rear junction n-type solar cells: Above 17.0% efficiency cells with CVD boron-doped epitaxial emitter

Epitaxial boron-doped emitters by CVD can provide a valuable alternative to the use of aluminum or diffused boron for the creation of p-type emitters. Compared to the traditional boron-diffused emitters for high-efficiency cells, epitaxial emitters need shorter process time, no boron skin removal step and have more opportunities to optimize the emitter doping profile. Our work proves that epitaxial emitters can be a good alternative for the p-type emitter. Very promising cell results with the highest cell efficiency of 17.0% on FZ material with LPCVD emitter and 16.7% on CZ material with APCVD emitter under 1 Sun have been achieved. Good fill factors have been obtained, which indicate good metal contacts are obtained on the epitaxial emitter. Cell results on n-type material are very encouraging and indicate a high potential of such epitaxial emitters for rear junction n-type solar cells.