Picosecond laser ablation and depth profile of Cu(In, Ga)Se2 thin film layer

Abstract

Laser ablation based on picosecond laser was used to achieve the micro-analysis of Cu(In, Ga)Se2 (CIGS) thin film with the ablation crater diameter of 50μm and the ablation crater central depth of 93 ± 13 nm. We achieved the depth profile of CIGS thin film with different laser shot number. The evolutions of spectral lines intensities of Ca from glass substrate and Ga and In from CIGS thin film layer, and intensity ratios of Ca/Ga and Ca/In could exhibit the change of the ablation volume, which could estimate the thin film thickness of single CIGS thin film layer. The average plasma temperature was calculated to be about 5243 ± 100 K, and the average electron density was calculated to be about 4.5×1016 cm−3. It is shown that our experimental setup is suitable to achieve a precise control and monitor the element compositions in each CIGS thin film layer in the research and in the production of CIGS solar cells.