Junction Resistivity of Carrier-Selective Polysilicon on Oxide Junctions and Its Impact on Solar Cell Performance

Abstract

We investigate the junction resistivity of high-quality carrier-selective polysilicon on oxide (POLO) junctions with the transfer length method. We demonstrate ${{n}}^{+ }$ POLO junctions with a saturation current density $J_{{\rm{C,poly}}}$ of 6.2 fA/cm2 and a junction resistivity $\rho _{{\rm{c}}}$ of 0.6 mΩcm2, counterdoped ${{n}}^{+ }$ POLO junctions with 2.7 fA/cm2 and 1.3 mΩcm2, and ${{p}}^{+ }$ POLO junctions with 6.7 fA/cm2 and 0.2 mΩcm2. Such low junction resistivities and saturation current densities correspond to excellent selectivities $S_{{10}}$ of up to 16.2. The efficiency potential for back-junction back-contact solar cells with these POLO junctions was determined to be larger than 25 % by numerical device simulations. We demonstrate experimentally a back-junction back-contact solar cell with p -type and n -type POLO junctions with an independently confirmed efficiency of 24.25 %.