SMART Cast-Monocrystalline p-Type Silicon Passivated Emitter and Rear Cells: Efficiency Benchmark and Bulk Lifetime Analysis

Herein, boron-doped cast-monocrystalline silicon wafers that have been fabricated using the Seed Manipulation for ARtificially controlled defect Technique (SMART mono-Si) are examined. Their suitability for passivated emitter and rear cell (PERC) fabrication is investigated. Applying a zero busbar layout energy conversion efficiencies of η = 21.9% for SMART mono-Si, η = 22.2% for gallium-doped Cz-Si (Cz-Si:Ga), and η = 22.3% for boron-doped Cz-Si (Cz-Si:B) are achieved at similar doping levels between 0.7 Ωcm ≤ ρB ≤ 1.0 Ωcm. Therefore, SMART mono-Si PERCs show almost the same performance as Cz-Si PERCs. Apart from the performance of SMART mono-Si PERCs, the minority charge carrier bulk lifetime τB of the SMART mono-Si wafers after different high-temperature process steps in the PERC process flow is investigated. After emitter formation, this analysis confirms the high material quality of SMART mono-Si yielding τB = 1.3 ms at an injection level of Δn = 10E15 cm-3. The bulk lifetime after firing is similar to the level determined for mCz-Si:B and Cz-Si:Ga reference wafers of similar doping level.