Research On Polycrystalline Silicon Solar Cell Preprocessing And Annealing Treatment

At present, many companies use tubular-pecvd equipment to deposit silicon nitride films in the solar cell industry. But there is a uniformity problem in the film thickness. In the reaction chamber, the response gas is not evenly distributed, so it will cause the differences in film thickness and this kind of situation will seriously affect the product’s efficiency.Through a lot of experiments in the production line, we found that the gas flow, air pressure and radio frequency power for uniformity have very big effect.380mm diameter,2075mm length of reaction chamber is commonly used.The most ideal deposition conditions is5000sccm total gas flow,4500w of radio frequency power and220pa of the pressure. In addition, the spacing size of graphite boat also has very big effect on the silicon nitride film uniformity. After comparing, we found13mm space is better than11mm space on the uniformity of film.The influence of hydrogen plasma by ammonia ionization preprocessing of MC-Si solar cells before deposition of SiNx thin films was described. The effect of prepr-ocessing time, RF power, temperature and the pressure were investigated. The short circuit current is higher than previous one. Then the silicon nitride (SiNx) was deposited for crystalline silicon solar cell by means of plasma enhanced chemical vapor deposition (PECVD), and the results indicated that the hydrogen plasma could walk through the silicon nitride and the carrier lifetime increased about7μs. The low temperature pretreatment could make efficiency of the short current and photoelectric conversion increased, the best range is430-440℃.