Self-Aligned, Selective Area Poly-Si/SiO2 Passivated Contacts for Enhanced Photocurrent in Front/Back Solar Cells
David L. Young, San Theingi, Vincenzo LaSalvia, Kejun Chen, William Nemeth, Dawn Findley, Matthew Page, Pauls Stradins
National Renewable Energy Laboratory, Golden, CO, United States

Poly-Si/SiO2passivated contact front/back solar cells suffer low Jscdue 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/cm2over 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 re-hydrogenation.