Application of induced laser ablation with ultra short pulse lasers for high speed thin film solar cell processing

Abstract

The monolithic serial interconnection of CIS thin film solar cells is performed with ultra short pulse laser radiation @ 1064 nm. We present an investigation of induced laser processes (often referred as “lift-off”). We show that the energy required to ablate a specific volume using induced laser processes is considerably reduced compared to direct ablation processes and that less thermal damage is induced to surrounding material.Direct induced (separation of a molybdenum layer through the glass substrate, P1) and indirect induced (transparent ZnO on absorbing CIS, P3) picosecond laser ablation are not purely thermal processes working at energies per ablated volume far below the evaporation enthalpy. With laser powers below 2 W process speeds of 6 m/s for the P3 process and 4 m/s for the P1 process have been achieved.The monolithic serial interconnection of CIS thin film solar cells is performed with ultra short pulse laser radiation @ 1064 nm. We present an investigation of induced laser processes (often referred as “lift-off”). We show that the energy required to ablate a specific volume using induced laser processes is considerably reduced compared to direct ablation processes and that less thermal damage is induced to surrounding material.Direct induced (separation of a molybdenum layer through the glass substrate, P1) and indirect induced (transparent ZnO on absorbing CIS, P3) picosecond laser ablation are not purely thermal processes working at energies per ablated volume far below the evaporation enthalpy. With laser powers below 2 W process speeds of 6 m/s for the P3 process and 4 m/s for the P1 process have been achieved.