Extended study on short pulse laser ablation ofdielectric layers with UV and VIS laser wavelength and pulse durations from fs to ns

摘要

A wide range laser pulse duration experiment was carried out including pulse durations from 25O femtoseconds (fs) to 3O nanoseconds (ns) based on four different laser systems. All laser systems are used to ablate PECVD SiO2/SiNX and PECVD-based nitride passivation stacks. Test structure samples for photoluminescence (PL) and scanning electron microscopy (SEM) analysis are ablated as well as typical line patterns for PERC solar cells and fluence test samples for all laser systems. These were configured as far as possible with identical aperture to beam ratio to generate comparable beam profiles and laser conditions. In addition standard multicrystalline (mc) solar cells are ablated on the front side as proposed in [1] to study laser damage effects due to the reduction of the pseudo fill factor (PFF). Thus a comparison of four different evaluation methods (SEM, PFF, PL, IV) for laser damage is carried out. Studies about the correlation between different laser parameters based on different evaluation strategies are presented.