Crystalline Silicon Solar Cells With PECVD Dilayer SiNx:H Thin Films

Silicon nitride(Si Nx: H)is an excellent dielectric film that has been widely used in photovoltaic devices.The surface antireflective and passivation of the emitter junction have always been the important part in the research of the crystalline silicon solar cells.The high efficiency crystalline silicon solar cells which requires good performance of the passivation layer of the emitter junction are as well as in need of good optical properties means the good the antireflection effect that can improve the the overall performance of the cell.Traditional antireflective films are Si Nx:H of single layer or Si O2/Si Nx:H of double-layer.In order to guarantee the light transmission,the single layer Si Nx:H has to sacrifice a certain of the passivation effect.This will results in a better photoelectric properties.The passivation effect of the silicon nitride film is closely related to its refractive index.The high-refractive index Si Nx: H film which has a higher density of Si-H bonds can effectively reduce the reverse saturation current obtaining a better passivation effect.While as for the optical effects of single-layer film it can not reach the high refractive index and can not fully play its excellent passivation effect.As for Si O2/Si Nx:H,on the one hand the passivation effect of Si O2 is not as good as Si Nx:H,on the other hand unlike the double-layer Si Nx:H the deposition can not be completed in one time and in single chamber.In terms of cost control,it is not as good as double-layer Si Nx:H.Given the above,this paper designed a double-layer silicon nitride film.The inner film is of high-refractive that can guarantee the excellent passivation effect.While the comprehensive optical effect is insured by the low-refractive outer film the passivation effect is ensured and will not cause optical loss.The plasma chemical vapor deposition(PECVD)which obtains a low reaction conditions and a high film quality has been widely used in the deposition of silicon nitride film.Based on the PECVD method,silicon nitride film is produced of the plate PECVD equipment.By adjusting the process parameters,different structures of silicon nitride film are grown including the different refractive index and thickness ofthe single-layer and bi-layer films.Comparative study found that the solar cell of bi-layer has a longer life time and the passivation effect is better than that of the single-layer.And for the bi-layer,the higher the refractive index of the inner,the more excellent battery performance.