Enhancement in photoelectric properties of ITO films by regulating defects and dopants with supercritical fluid treatment

Abstract The carrier concentration of the indium tin oxide (ITO) thin films can be enhanced by supplying extra conducting electrons with tin dopants. However, defects and impurities, which are rich around grain boundaries, result in strong carrier scattering. In this work, ITO films prepared by magnetron sputtering were subjected to supercritical carbon dioxide (SCCO2) fluid treatment with different concentrations of InCl3 solutions, In3+ ions were introduced in the grain boundaries for the purpose of regulating defects and impurities there. The photoelectric performance of ITO films was improved significantly after the SCCO2 fluid treatments, which was interpreted for the effects of SCCO2 on as-deposited ITO microstructures based on the experimental results of X-ray photoelectron spectroscopy and positron annihilation lifetime spectroscopy. Upon the SCCO2 fluid treatment, the dehydration effect passivated the dangling bonds around the grain boundaries, meanwhile, the indium ions diffused into the grain boundaries, resulting in the formation of ITO-like lattice structure there.