Research Of Surface Passivation On Silicon Solar Cells

Generating electricity by solar cells becomes one of the significant methods to solve the shortage of energy and environment pollution. Currently, more than 80% of solar cells are made from crystalline silicon, so it is very important to develop high efficiency and low cost crystalline silicon solar cells. The front surface passivation and rear surface passivation are two key procedures in the process of high efficiency crystalline silicon solar cells. By measuring the lifetime of the samples, we do some experiment researches on surface passivation technology.The passivation technologies of high efficiency silicon solar cells in laboratory were systematically reviewed in this paper. In the third chapter, we aimed at the surface passivation with high doping levels, and researched the influence of oxidation temperature and time to the effect of front surface passivation. By analyzing the lifetime and the Voc of silicon solar cells, we found that we can get good surface passivation under the condition of 840℃and 10 minutes. Using this condition, we can reduce the influence of high temperature to silicon in the oxidation process, and also can maintain the good surface passivation.In the forth chapter, we aimed at the SiN rear surface passivation, and researched the annealing characteristics of conventional thermal process(CTP) and rapid thermal process(RTP) of SiN films, at the same time we did the experiment of SiN rear surface passivation solar cells. By the experiment of annealing characteristic of CTP, we found that SiN film was fit to annealing under the temperature of 500℃, and the SiN/SiO2 film was fit to annealing between the temperature of 600℃and 700℃. When annealing above the temperature of 800℃, all the two films lost the effect of surface passivation. By the experiment of annealing characteristic of RTP, we found that SiN film can get good surface passivation annealing between the temperature of 700℃and 850℃, and when annealing above the temperature of 900℃, we must choose the more rapid velocity. By the experiment of SiN rear surface passivation solar cells, we made the rear surface point-contact electrode with diameter of 300um and space of 2mm using screen printing technology, and the Voc of silicon solar cells achieved to 628mv.