Wavelength dependence of the ablation characteristics of Cu (In, Ga) Se2 solar cell films and its effects on laser induced breakdown spectroscopy analysis

Abstract

As a novel method for fast depth profile analysis of Cu (In, Ga) Se2 (CIGS) thin film solar cell, laser induced breakdown spectroscopy (LIBS) is introduced, and the effects of laser wavelength on depth resolution are investigated. From LIBS analysis of a commercial CIGS solar cell using an ultraviolet (λ = 266 nm) and a visible (λ = 532 nm) nanosecond Nd: YAG lasers and an intensified charge-coupled device spectrometer, it is shown that the use of a shorter wavelength laser does not guarantee an enhancement of depth resolution. Although the averaged ablation depth per pulse was smaller for the ultraviolet laser, the craters produced by the visible laser was much smoother and more uniform, demonstrating that depth resolution depends not only on laser wavelength but also strongly on the ablation mechanisms.