A novel and effective PECVD SiO2/SiN antireflection coating for Si solar cells

It is shown that sequential plasma-enhanced chemical vapor deposition (PECVD) of SiN and SiO₂ can produce a very effective double-layer antireflection (AR) coating. This AR coating is compared with the frequently used and highly efficient MgF₂/ZnS double layer coating. The SiO₂/SiN coating improves the short-circuit current (J_SC) by 47%, open-circuit voltage (V_OC) by 3.7%, and efficiency (Eff) by 55% for silicon cells with oxide surface passivation. The counterpart MgF₂/ZnS coating gives similar but slightly smaller improvement in V_OC and Eff. However, if silicon cells do not have the oxide passivation, the PECVD SiO₂/SiN gives much greater improvement in the cell parameters, 57% in J_SC, 8% in V_OC, and 66% in efficiency, compared to the MgF₂/ZnS coating which improves J_SC by 50%, V_OC by 2%, and cell efficiency by 54%. This significant additional improvement results from the PECVD deposition-induced surface/defect passivation. The internal quantum efficiency (IQE) measurements showed that the PECVD SiO₂/SiN coating a absorbs fair amount of photons in the short-wavelength range (<500 nm); however, the improved surface/defect passivation more than compensates for the loss in J_SC and gives higher improvement in the cell efficiency compared to the MgF₂/ZnS coating