Passivation quality control in poly-Si/SiOx/c-Si passivated contact solar cells with 734 mV implied open circuit voltage

Abstract

Passivation quality of poly-Si contacts with different phosphorus doping concentration were investigated in this study. Intrinsic poly-Si layers were deposited by LPCVD on a tunnel oxide surface, followed by n + poly-Si doping and hydrogenation. For lightly doped poly-Si contacts with phosphorus concentration of 2.1×1019cm−3, higher temperatures and longer times increased iVOC achieving maximum value of 734 mV, as poly-Si grain size increases from 13 nm to 40 nm. However, for heavily doped poly-Si contacts with phosphorus concentration of 1.1×1020cm−3, iVOC decreased from 731 mV to 696 mV as annealing time increased from 10 to 60 min because Auger recombination rate increased from 9.3fA/cm2 to 21.6fA/cm2 as phosphorus in-diffusion occurs. The contact resistance of poly-Si contacts was also investigated to achieve a high fill factor. Finally, a poly-Si/SiOx/c-Si passivated contact solar cell using a poly-Si contact on the back and boron diffused emitter on the front was fabricated. As a result, high efficiency of 21.1% solar cell was achieved with VOC of 665 mV, JSC of 40.6 mA/cm2, and fill factor of 78.3%.