Polysilicon contact structures for silicon solar cells using atomic layer deposited oxides and nitrides as ultra-thin dielectric interlayers

Polysilicon contact structures with ultra-thin atomic layer deposited (ALD) oxide and nitride interlayers based on SiOx, SiNx, AlOx, AlNx, and TiOx either as part of an interlayer stack when applied on top of a conventional thermally-grown SiOx or as a single interlayer were investigated. ALD SiOx single interlayers provided a very good passivation quality with high implied open-circuit voltage and low-specific contact resistivity when an optimal thickness and annealing temperature was applied. Also, ALD SiNx single interlayers showed a promising passivation quality, while AlOx and AlNx interlayers only allowed for a moderate and TiOx interlayers exhibited a very poor passivation quality. ALD SiOx interlayers on planar and textured silicon solar cells with poly-Si(p) hole-selective contacts and poly-Si(n) electron-selective contacts enabled a conversion efficiency of almost 21% as a proof-of-concept. These results are comparable with silicon solar cells with conventional thermally-grown SiOx, showing that ALD SiOx interlayers are an alternative to conventional thermally-grown SiOx in polysilicon contacts structures.

Automated summary

Polysilicon contact structures were investigated with ultra-thin atomic layer deposited (ALD) oxide and nitride interlayers, showing that ALD SiOx single interlayers provided good passivation quality while ALD SiNx single interlayers also showed promising passivation quality. However, AlOx and AlNx interlayers only allowed for a moderate effect, and TiOx interlayers exhibited very poor passivation quality.