PERC Solar Cells on p-Type Cz-Si Utilizing Phosphorus-Doped SiNX Layers

We apply phosphorus-doped silicon nitride (SiN
_X
:P) layers on the front surface of
p
-type Czochralski-grown silicon (Cz-Si) passivated emitter and rear cells (PERC). The layers are formed using industrial-type plasma-enhanced chemical vapor deposition. They provide excellent surface passivation with implied open-circuit voltages
$\text{i}V_{\text{OC}}$
up to 695 mV and similar optical properties as conventional undoped SiN
_X
anti-reflection layers with
$\text{i}V_{\text{OC}}$
peaking at 685 mV. The emitter dark saturation current density at the passivated textured surface is
$j_{\rm 0e}$
≈ 40 fA/cm² for a lowly-doped emitter with sheet resistance
$R_{\text{sh}}$
≈ 160 Ω/sq. For realizing laser-doped selective emitters (LDSE), local laser processing is applied to introduce additional dopants from the SiN
_X
:P layer into the silicon. Thereby, highly doped areas are formed in which
$R_{\text{sh}}$
is decreased down to 55 Ω/sq. We refer to this as the nPassDop approach, which provides both local high doping and local structuring of the anti-reflection coating in a single process step. Low contact resistivity of around 1.5 mΩcm
²
is measured for screen-printed and fired silver contacts on the locally laser-doped areas. A first proof of concept of large-area
p
-type Cz-Si PERC solar cells with front side
$\text{SiN}_{\text{X}}\text{:P}$
passivation and LDSE structure yield energy conversion efficiencies up to 20.9%.