Abstract
In industrial process, n+ doped region of solar cell often be fabricated by POCl3 diffusion. However, POCl3 is toxic and harmful to the environment. As for p+ doped region, it often be made with BBr3, but BBr3 is toxic and easy to form HBr when it was used. In this research, n+ doped and p+ doped region was fabricated by spraying of dilute phosphoric acid and boric acid as doping source. After comparing the doping profile and sheet resistance, phosphorus diffused at 950℃/30min will get proper n+ doped region. Besides, spraying dilute boric acid 600s before diffusing at the same temperature and time will also have the proper doping result of p+ doped region. Furthermore, by using the Boltzmann-Matano method to analyze the diffusion mechanism of phosphorus and boron. The results shows that phosphorus diffusion was dominated by vacancy、self-interstitial silicon atoms and interstitial phosphorus atoms at different concentration regions. As for boron diffusion mechanism, it was dominated by vacancy and self-interstitial silicon atoms when boron atoms diffused. At last, by using spraying technique and co-diffusion to fabricate n+ and p+ doped region of solar cells. After measurement, monocrystalline solar cell can get the efficiency 15.57% and bifacial solar cell can get the efficiency 7.86% in respective.