Time-resolved photoluminescence for evaluating laser-induced damage during dielectric stack ablation in silicon solar cells

Highlights: • Ablation of Al₂O₃ and Al₂O₃/SiN_x on Si substrates was performed with a nanosecond UV laser. • Ablation thresholds were found in good agreement with COMSOL simulation, around 0.85 and 0.95 J cm⁻² for Al₂O₃ and Al₂O₃/SiN_X, respectively. • Laser-induced damage was evaluated at room temperature by time-resolved photoluminescence decay with a single photon counting detector. • Minority carrier lifetime in silicon as a function of the ablation fluence was derived from the photoluminescence decay and related to the thickness of the heat affected zone. • Quantitative measurements of laser-induced damage can be used to evaluate laser ablation of dielectrics in photovoltaics. - Abstract: Selective laser ablation of dielectric layers on crystalline silicon wafers was investigated for solar cell fabrication. Laser processing was performed on Al₂O₃, and bi-layers Al₂O₃/SiN_X:H with a nanosecond UV laser at various energy densities ranging from 0.4 to 2 J cm⁻². Ablation threshold was correlated to the simulated temperature at the interface between the dielectric coatings and the silicon substrate. Laser-induced damage to the silicon substrate was evaluated by time-resolved photoluminescence. The minority carrier lifetime deduced from time-resolved photoluminescence was related to the depth of the heat affected zone in the substrate.