Progress in research on laser annealing technology of indium tin oxide thin films

- Nov 17, 2020-

Recently, the Thin Film Optics Laboratory of the Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences has made new progress in the research of 1064nm quasi-continuous laser annealing indium tin oxide (ITO) films, and found that the quasi-continuous laser annealing induces changes in the surface morphology and temperature rise of ITO films. Dependency. Related results were published in "Optical Materials Express" 

ITO is one of the most important transparent conductive electrode materials and is widely used in photovoltaic devices such as solar cells, electro-optical switches, and liquid crystal devices. In ITO preparation and annealing, temperature is one of the key factors that affect the performance of ITO thin films. Proper annealing temperature can improve the crystallinity, surface roughness and photoelectric properties of the film. However, excessively high temperature, especially the rapid temperature rise induced by laser, causes damages such as cracking, melting, evaporation, and ablation of the film. These thermal phenomena of ITO thin films mean that the properties of ITO thin films can be improved by optimizing the laser annealing temperature.

The research group used a high average power 1064nm quasi-continuous laser to achieve a slow increase in the annealing temperature, and realized the control of the temperature field distribution of the ITO film by designing ITO films of different thicknesses. It was found that in the quasi-continuous laser annealing ITO film, once the annealing temperature reaches ~520K The deformation or crack temperature threshold of ~1250K, the corresponding deformation or cracks will appear on the surface of the film. The initial surface deformation or crack size is consistent with the size of the area where the surface temperature is higher than the deformation or crack temperature threshold. This study clarified the influence rules and mechanisms of quasi-continuous laser annealing on the morphology of ITO films, and provided important guidance for the optimization of quasi-continuous laser annealing process and the application of technology.

  Research work is supported by the National Natural Science Foundation of China, the Strategic Key Research Project of the Chinese Academy of Sciences and the Open Research Fund of the State Key Laboratory of Pulsed Power Laser Technology.