Rapid micro-analysis of Al-In-Sn-O thin film using laser induced breakdown spectroscopy with picosecond laser pulses

Laser induced breakdown spectroscopy (LIBS) based on picosecond laser pulses was used to achieve rapid micro-analysis of Al-In-Sn-O (AITO) thin films deposited by radio frequency (RF) magnetron sputtering at various sputtering powers. We calculated the plasma temperature of 5063 ± 150 K and electron density of 4.6 × 1016 cm−3 with single ablation crater diameter of 46 ± 1 μm. The content ratio of Al/(Al+In+Sn) in AITO thin film was closely related to the optical band gap of the film, and the ratio was exhibited by the spectral line intensity of LIBS for each corresponding element. The quantitative analysis of Al/(Al+In+Sn) with LIBS intensity ratio was achieved by plotting calibration curves according to the value of energy dispersive X-ray spectroscopy (EDS). It was found that the optical band gaps calculated were decreasing as the increase of the sputtering power in the exhibition of the transmittance spectra of AITO thin films deposited at various sputtering powers. In addition, we found the consistency of the evolutions of LIBS target line intensity ratio and optical band gap of AITO thin films. Therefore, the utilization of LIBS based on picosecond laser pulses is available and efficient in the rapid micro-analysis of AITO thin film.