Layer transfer process assisted by laser scribing for thin film solar cells based on epitaxial foils

摘要

The lift-off step of a layer transfer process for the production of thin-film solar cells using a double porous layer is studied in detail.The goal is to loeally weaken the thin film to improve the deachment. A UV nanosecond pulse laser is used to induce the weakening by scrbing trenches,A relation between the pulse fluencc,the number of pulses per point and the ablated area is found and used to prediet the ablation depth.The grooving step is applied at different points in the process chain. The omst suitable grooves are obtained when the scrbing process is done after front-step. A yield of around 80% is obrained for samples that went through the process chain up to the detachment step,by using the optimized process conditions. SEM of the mother substrate (right) and the remaining of the thin film (left) after detachment oi'the useful foil area. The white points on the substrate are the leftover of the pillars from the weak layer.