Role of Polysilicon in Poly-Si/SiOx Passivating Contact Solar Cells

We investigated the passivation qualities of polySi contacts according to several material and fabrication properties to study their role in improving the efficiency of solar cells. Our observations indicate that P in-diffusion degrades the implied open circuit voltage (iVOC), while gettering increases it. Thick, highly doped poly-Si is needed for high iVOC; however, this increases parasitic absorption. Hence, we suggest a new approach to fabricating highly doped, thin poly-Si contact, with high iVOC, via etch-back. On etching, the iVOC remained at its original value until the poly-Si was fully etched, and we obtained an improved solar cell efficiency of 20.59%.