Co-Etching Process for Boron-Rich and Phosphorus-Rich Layers in Crystalline Silicon Solar Cells

• • Optimal co-etching condition: HF:HNO3:H2O = 1:5:20 by volume for 5 min achieves simultaneous removal of boron-rich and phosphorus-rich layers, eliminating a separate KOH etching step and reducing process complexity by approximately 30% in terms of unit operations. • • Minority carrier lifetime improves from <20 µs (as-diffused, unpassivated) to 75.7 µs after Nafion passivation, and iVoc increases from 585 mV to 610 mV, directly correlating with reduced surface defect density and enhanced passivation quality. • • The co-etching process modulates sheet resistance of both front emitter and back surface field to meet commercial requirements, enabling precise control over doping profiles and junction depth without compromising the pyramidal light-trapping texture. • • Elimination of separate BRL and PRL removal steps reduces chemical waste volume and processing time, with potential cost reduction of 15–20% in wet processing for n-type PERT solar cell manufacturing.