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

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
_C,poly
of 6.2 fA/cm
²
and a junction resistivity ρ
_c
of 0.6 mΩcm
²
, counterdoped n
⁺
POLO junctions with 2.7 fA/cm
²
and 1.3 mΩcm
²
, and p
⁺
POLO junctions with 6.7 fA/cm
²
and 0.2 mΩcm
²
. 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 %.