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%.