Application of PECVD SiNx films to screen-printed multicrystalline silicon solar cell

Silicon nitride (SiNx) film is a promising material for anti-reflection coating and passivation of multicrystalline silicon (mc-Si) solar cells. In this work, a plasma-enhanced chemical-vapor deposition (PECVD) system with batch-type reactor tube was used to prepare highly robust SiNx films for screen-printed mc-Si solar cells. The gas flow rate ratio, R = [SiH4]/[NH3], in a mixture of silane and ammonia was varied in the range of 0.091 - 0.235 while fixing the total flow rate of the process gases to 4,200 sccm. The refractive index of the SiNx film deposited with a gas flow rate ratio of 0.091 was measured to be 2.03 and increased to 2.37 as the gas flow rate ratio increased to 0.235. The highest efficiency of the cell was 14.99 % when the flow rate of SiH4 was 350 sccm (R = 0.091). Generally, we observed that the efficiency of the mc-Si solar cell decreased with increasing R. From the analysis of the reflectance and the quantum efficiency of the cell, the decrease in the efficiency was shown to originate mainly from an increase in the surface reflectance for a high flow rate of SiH4 during the deposition of SiNx films.