Towards ultra-low detection limits of lithium by LIBS in LiF atomic layers

The growing number of industrial applications requiring thin-film materials is prompting the development of new characterization methods. We demonstrate that laser-induced breakdown spectroscopy (LIBS) enables the verification of the spatial homogeneity of LiF films deposited by atomic layer deposition (ALD), and quantify the amount of lithium in LiF thin films. In our experimental conditions, we obtained a limit of detection (LOD) of 0.7–4.1 fg.ng −1 for the Li I line at 670.8 nm and for single-shot LIBS analysis. Then, an estimate of LOD in the range 0.17–0.93 fg.ng −1 (i.e. 170–930 ppb) was obtained with other acquisition parameters. Given the 100 Hz repetition rate of the laser shots, the LOD decreases by a factor of 10 in one second leading to 0.012–0.065 fg/√Hz. Such level of detection limit paves the way for future utilization of LIBS for the chemical characterization of thin films. • Deposition of LiF uniform thin films on Si wafer by atomic layer deposition. • Calibration curves for Li by Laser Induced Breakdown Spectroscopy. • LIBS imaging of LiF thin films. • Determination of LOD for Li as low as 170–930 ppb (mass ratio).