Thin layer ablation with lasers of different beam profiles: energy efficiency and over filling factor

Abstract

Structuring and patterning of thin layer via selective laser ablation is one of the key technologies in production of display and photovoltaic. Concurrently, there are two ablation processes used in production of thin film solar cells: Scribing via selective ablation and edge isolation via deletion. The common laser beams have circular cross section. Furthermore, the most currently lasers of high beam quality have Gaussian beam profile. Because of threshold behaviour Gaussian beam profile is not favourable for ablation process. On the other side there are emerging laser concepts which deliver rectangular or saqure top-hat beams with high beam quality. In this paper we will discuss the fundamentals of ablation processes with circular Gaussian beams, one dimensional top-hat beams and two dimensional square top-hat beams. The major issues will be the energy efficiency of the process and the area over filling aspect for the different beam profiles. The corresponding experimental results will be presented.