Self-Aligned, Selective Area Poly-Si/SiO2 Passivated Contacts for Enhanced Photocurrent in Front/Back Solar Cells

Poly-Si/SiO2 passivated contact front/back solar cells suffer low Jsc due to parasitic absorption in the front poly-Si layer. We demonstrate a self-aligned, selective area front contact dry-etch technique that retains the as-deposited poly-Si beneath the metal grid lines but thins it elsewhere. Jsc improves by 0.7 mA/cm² over our standard 40 nm thick poly-Si. Greater improvements are expected with thicker poly-Si needed for fired metal contacts. Surface passivation is slightly diminished with poly-Si thinning but can be partially restored with rehydrogenation.