A novel and effective PECVD SiO/sub 2//SiN antireflection coating for Si solar cells

It is shown that sequential plasma-enhanced chemical vapor deposition (PECVD) of SiN and SiO/sub 2/ can produce a very effective double-layer antireflection (AR) coating. This AR coating is compared with the frequently used and highly efficient MgF/sub 2//ZnS double layer coating. The SiO/sub 2//SiN coating improves the short-circuit current (J/sub SC/) by 47%, open-circuit voltage (V/sub OC/) by 3.7%, and efficiency (Eff) by 55% for silicon cells with oxide surface passivation. The counterpart MgF/sub 2//ZnS coating gives similar but slightly smaller improvement in V/sub OC/ and Eff. However, if silicon cells do not have the oxide passivation, the PECVD SiO/sub 2//SiN gives much greater improvement in the cell parameters, 57% in J/sub SC/, 8% in V/sub OC/, and 66% in efficiency, compared to the MgF/sub 2//ZnS coating which improves J/sub SC/ by 50%, V/sub 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 SiO/sub 2//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/sub SC/ and gives higher improvement in the cell efficiency compared to the MgF/sub 2//ZnS coating.<
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